"Can anyone recommend an experienced fitter for wood flooring."
Yes but here is not an appropriate place and I don't know where you are.
"Also what sort of thing should I look out for in choosing a fitter, are there any trade bodies they may belong to for example?"
Most of these so called trade bodies are little more than clubs which, having paid the subscription, entitle you to say " I belong so so-and-so". Get recommendations. Invite 3 round to quote. You'll soon get a feel of who a) knows whathe is talking about and b) is trustworthy.
"Can a builder do the job just as well?"
Probably he'll just sub it out and take his percentage off the top.
"Finally if anyone would like to fire off some prices for fitting and materials per square metre that would be helpful as I look for good value."
My local shop uses fitters that charge £ 25.00 per sqm. Is that good value? How do you measure "good value"? Cheap doesn't necessarilly mean good.