If you feel more comfortable doing this then by all means go for it, but honestly it’s unnecessary and you would be fine just jumping straight into a plan and going for it. Your test result isn’t a punishment, it’s just a reflection of where your fitness is right now. You’ll get your old fitness back in pretty short order.
I would recommend coming back to training to select the Low Volume plan initially. That’s 3 rides per week of about 1 hour each. So, the rides when you’re in them feel challenging, but in reality isn’t a huge training load. You’ll have rest days after all your rides so recovery will take care of itself. As for nutrition I would point you to this thread Nutrition books. Lots of good resources in there, but you can’t really go wrong with Matt Fitzgeralds book.