As far as I've been able to research, there's nowhere even in the London area (where I live) where this is possible. I found an older Gearslutz thread that suggested Digital Village, who had a number of stores in the area, but they were all closed down about six months ago after a sudden takeover of the company. There is a (now rare) music store about three miles from me that sells monitors, but only KRK. No doubt, the internet has killed them all off.