I found Gunman Airsoft Midlands today which is about 20 minutes from where I live (which was handy).
I definitely see what you mean about holding different guns and getting a feel for them. The UMP was spot on for me and the owners there were really helpful and let us shoot a GBBR (not loaded of course) to get a feel for the it and man they have some kick!
I'll be doing my first skirmish next month hopefully and then I'll go for my Defence.
The UMP they had there was an Umarex, now I'm a bit unsure about buying Umarex as the guys at Airman said Umarex don't make the guns they just rebrand other guns and sell as their own?
Is there a risk I'll buy a bad Umarex if there's various companies they rebrand from?