.. I think learning to fly out of a bigger airport certainly helps with your overall confidence. People seem to have no problem with the transition from a bigger airfield to flying out of a smaller one, but don't usually find it as easy vice versa.
I'm not sure I agree that the additional confidence allegedly imbued from learning to fly at a large commercial airport necessarily offsets the extra expense of landing/handling fees and the hassle of long taxis to the hold and delay at the hold with the clock ticking while commercial traffic gets preference.
Sure Norwich is a great place and the ATC second to none but the attitude to GA over the last few years has driven many away (including me).
And the proposed Class D around Norwich which is under discussion has not yet been kicked into the long grass.
A little bird tells me that a new management structure will attempt to woo back GA by easing red tape: time alone will tell.
If the OP lives near Norwich my advice would be to go and see all the Flying schools at Norwich but also to drop in to Old Buckenham. I don't know anything about Seething, but it's close enough to warrant a visit too.
The notion that a PPL who trained at a small airfield will not be able to cope with procedures at a large commercial airfield is an urban myth.