Hey,
I am a Norfolk boy 😉 Not doing the route, but ride the roads all the time. The best way to do it is to work on how hard it feels. Road riders around here tend to work around “sprints” a lot, but the secret is to keep the legs muscles from going into the red too much, or you will suffer later in the ride. Try to keep it as consistent as possible.
There are the occasionally little hill, which usually has a slight run in, so make the most of them and try to carry as much speed through as possible.
Whilst it may be flat, the head winds off the North Sea are brutal. Keep low on the drops and as aero as possible. Where possible, draft other riders and chat lots 🙂 Plenty of my club mates are going to be doing it, and they’re really, really approachable – look out for Iceni Velo jerseys and get chatting!
When people from hilly areas ride and race around Norfolk, they complain that they have to keep on the gas all the time, as they don’t get time to recover on the descents. Let me know how you do and have fun.