Minispeed (01932 400 567) in Byfleet are good (not London but inside the M25 at least) and they have a rolling road, not sure of the price (guessing £50-100 per session) but they might give you some advice over the phone re: needle choices for your set up; 998 stage 1 is pretty common so should be able to get it close enough.
Minispeed (01932 400 567) in Byfleet are good (not London but inside the M25 at least) and they have a rolling road, not sure of the price (guessing £50-100 per session) but they might give you some advice over the phone re: needle choices for your set up; 998 stage 1 is pretty common so should be able to get it close enough.