Just by way of an update - had my first hour in the skies yesterday
No question now that I want to pursue my PPL and as others have mentioned, I think it'll be better if I get it done asap rather than dragging it out.
I went up to Sibson to try out the Robin and whilst I have nothing to compare it to, it was certainly great fun to fly. I was amazed how sensitive the controls were but it was very manageable and very quickly became second nature keeping it straight and level, turning etc.
I have visited Bourn as well, which whilst not having the facilities of Sibson was very friendly and relaxed. I also intend to pop in to Conington to have a look around. However, I was impressed with with the set up at Sibson therefore my gut feeling is that now I've started there in the Robin I should probably continue.