If all you want to do is use the camcorder to record tapes in American format, then bring it along. So long as you have a dual-voltage charger or use a transformer (to change 240V U.K. supplies down to 120V), it will be fine.
The only issue is when it comes to viewing those tapes on a British TV set, which may or may not correctly display NTSC (American) video signals, or if you want to play back the tapes on a British VCR.
Some televisions actually have a NTSC tuner in them.
Just to clarify the situation, very few domestic TV sets here have a tuner section which will work with NTSC, but many modern sets will accept NTSC on the direct video inputs. There are also a large number of VCRs on the market now which will also play back NTSC tapes.