Glad you enjoyed yourself!
I ride Cannock with a few mates every couple of months. It’s good fun, although not very challenging technically (the Red, that is).
We tend to average around 1:50 for the complete loop; i’d describe my fitness levels as “average”, so 3 hours will give you plenty of time for snacks / breaks / enjoying the scenery.
The next time i go, i fancy taking that bike with none of those gear-y things…
Edit – anyone else who fancies going there, get used to riding on cobblestones!