In reply to SandmanOCR:
I recently did as suggested above, I went to my local climbing shop in MK and tried on many different varieties. The staff were great and even had me trying on shoes out of my budget range just to find a suitable shoe, sadly with the stock they had in I didn't find a pair. I did leave however better armed with the knowledge of how a shoe should fit.
I visited Go Outdoors and purchased some ClimbX shoes for £38, I'm not yet convinced I got exactly the right size but time will tell. The MK shop had very limited stock so I went to the Nottingham branch when visiting family where they had loads out on the shop floor allowing me to try as many on as I liked.
Ideally I would have liked to support the local shop, hopefully next time when I have a larger budget.
Good luck!