Without personal data, I’m sure there would be shops in Lydd or Rye or New Romney.
Depending on your schedule, and COVID permitting, why not drive your approximate route first so you have an idea of where there might be a good store?
But there’s certainly some nice cycling out that kind of way, try and avoid a really windy day!
Good luck from a Man of Kent 
Perfectly understandable to not want to stop. However you need to come up to the reality that it’s very difficult to carry 100 miles worth of fluids. So, you may need to make a pitstop but that does not mean it has to be a full-blown meal at a café. (Although you definitely want to do some rides where you just randomly stop at cafés and eat stuff. That’s one of the joys of cycling too 
Dash into a convenience store or gas station, buy a gallon of water, refill your bottles and get on your way. Or, just scout out some parks on your route and have water fountains at work. Think of it like a pitstop in a car race. It’s just part of the race. Make a plan, make it quick, and you’ll have a faster overall ride than if you try to struggle through without stopping.
100 miles of fluids would be both cages, 2x bar bottle pack things and prob a 5th squishy bottle in my jersey. That’s still only 3lt at best, although if the weather is a crap in June as recently 4 hours on 3lts could just work if you start loaded up.
Any big distance racing unsupported doesn’t stop you getting more liquid/food from a café/garage/corner shop. You often hear of the mad trans continent racing grabbing a night in a B&B for getting good quality sleep/food once in the week. Unsupported, in my mind at least, just means no outside help.
Go shopping with my own card is me refuelling, and you will go faster keeping the tank topped up.
Last year did solo 91 miles on flat roads with 800+ feet of ‘climbing’ 
and only 12.5 minutes downtime from 2 stops:
Wished I had re-routed for water at the second stop. Starting temp was 70F / 21C and ending temp 90F / 32C. That was really a 9 bottle ride and I did it with 6 bottles - performance suffered the last 30 minutes!
I have done a few 200 km brevets and I’m going for back to back century rides on Friday and Saturday (travelling from Madrid to the Mediterranean coast of Spain). I’ll be carrying some bikepacking bags, and there are about 2000 meters of climbing the first day, and 1500 on the second day.
I tend to eat too little “bike food” and stop regularly in cafes (like, every couple of hours or thereabouts). I tend not to check the maps beforehand for good spots for stops, I just go by feel.
I tend to pace myself a tiny bit too hard and have some miserable 10-15 miles at the end. I go low tempo on the flats and sweet-spot on the climbs , there aren’t terribly long climbs on the route.
I’ll try a maltodextrin, table sugar and electrolite mix concoction I’ve been experimenting with during training rides. I am learning to sip a bottle with 80 grams of sugars at the right rate , that should last me for about a couple of hours.
I think that since I fuel with this mix, which is more gradual than having a gel, I sustain about 10-15 more watts in 2-3 hour rides (I might be seeing things that aren’t there…)
The simplest way is to stop to refill your bottles somewhere half way. Either buy a bottle of water in a shop/petrol station, or ask the internet if there is any public drinking water somewhere.
If you don’t want to do that, you could also deposit a bottle somewhere as sort of self-supported pit stop.
Or plan your route so you do two 50 mile loops with your house (or a friends, or even your workplace) in the middle.
Depends how much you think you’ll drink, personly I could do that distance on two bottles, unless it was roasting hot, but I would usually stop and buy a drink somewhere in addition to what I carry.
a good goal and something that can, with the ideas of the other folk who have responded, possibly be achieved. But it’s always good to have an idea of where you could get supplies if you find that were extra hungry or thirsty early on and run out before the end. as others have said, self sufficient is fine but it’s still self supported if you’re the one finding the support. the gravel century i did last summer only had one official aid station around mile 40 and i ran out of water late in the game only the ask a nice lady that was working in her garden if i could fill up at one of her hoses. nice indeed, she went inside to fill my bottle with filtered (brita) water. things were much easier after that.
Water can be had from most big buildings (except in winter) because they have outdoor taps. Usually the handle isn’t there, but with one of these keys, you can turn on the tap:
I think it’s called a sillcock key.
Do like 75% ftp, and make sure you have enough calories and fluid. If you need to, do 2 50 mile loops so you can swap out bottles half way through with fresh ones that you pre-made
Many thanks to all of you that replied. You’ve certainly given me a lot to think about. I’ll try incorporating much of the advice and fingers crossed I’ll complete the ride in the summer.
Sorry I can’t reply to everyone individually. I had a go last night but am a bit pressed for time at the moment.
For locks for quick stops, I have one of these. It is lightweight, cheap, and compact. This will stop/significantly slow down someone without tools. If they have tools, then you really need a big, heavy lock to deter them - I don’t think there is value in middle-weight locks (aka ottolock, etc).
Some of these hyped-up locks (Ottolock, for example) seem to be trivially easy to open using typical thief’s tools. This well-regarded Youtuber has a bike-lock playlist where he shows what’s needed to get into many of the market-leading bike locks:
[1285] Abus Bordo Lite Folding Bike Lock Picked (Model 6055) - YouTube
Here’s Ottolock, for example:
The point of these locks is that it deters opportunists, not necessarily bike thieves. Sometimes you need something, anything that is better than nothing. I’ve reverted to literally hiding my bike in a bush because I had to unexpectedly run into the store for 2 minutes. Even if I had a rope that I tied a bunch of knots in I would have used to slow down the local idiot that sees a free bike.
Agreed! Your determined bike thief is going to be coming to ‘work’ equipped with the tools of his ‘trade’ - tin snips, bolt cutters, angle grinder or whatever needed to overcome any bike locks. They know the bike is likely to be unattended for a while and they target high density / commuter areas.
These light locks are aimed at a mid-ride stop when the bike is left unattended for only a couple of minutes outside a store / coffee shop in the middle of nowhere. The chances of bumping into a tin snips wielding bike thief in those few minutes at that location must be extremely remote and realistically the alternative to taking a light lock is taking nothing!
I’m lucky enough to have a small frame and have a generally easy terrain to ride in, so at an easy pace I can comfortably get away with not stopping. My last solo century was on my TT bike and I just had one bottle which was plenty as the ride was mostly cruising in zone 2 on a flat terrain. I can’t remember what I had in my pocket (maybe a banana, a bar or two and a gel for emergency).
Close to Home | Ride | Strava
My weekend century wasn’t solo (only the last 25miles of the 134 miles were), so the tempo although relaxed mostly wasn’t as as controlled and it was on a bit hillier terrain so a bottle refill/ cafe stop at 80miles was good to keep it functional 
