That sounds like a good plan!
Honestly, I wouldn’t focus too much on fat utilization, but yes, Sweet Spot will improve those capabilities to some extent among other things. 
There are pros and cons to both Traditional Base and General Base training but in my opinion, I would pick General Base every time unless you have a minimum of 12+ hours each week to train.
You’re right, there are certainly a lot of opinions regarding Sweet Spot training, Zone 2, and well, just about every single other thing in cycling. 
It’s really common to hear that one singular philosophy is superior to all others, and it’s interesting to watch the tides come and go as new research emerges regarding any one specific topic or when one particular sports scientist/exercise physiologist starts trending over another. It seems like things come around full circle after a while, so while it’s important to pay attention to what’s being discussed, it’s also important to avoid getting too distracted by all of the constant noise and focus on finding out what works best for you. We each have our own life circumstances, genetics, etc. that we have to figure out how to work with. 
Again, for someone in your situation, I’d recommend starting with General Base to see where that gets you, and you can always switch things up if you’d like along the way! Sometimes trial and error is the only way to figure out your own recipe for success! 
If you’re interested in learning more about Sweet Spot training check out the link below!
Let me know if I can help out with anything along the way! 