Most modern VCR's support both PAL (UK) and NTSC (USA) vids. If you VCR doesn't then you can still play it, but it will be in black and white (and won't do your tape/VCR much good so be warned) Also make sure your TV is fairly modern as well as i had a PAL/NTSC VRC and it plays American Vids fine, but i used it round my Parents on there (Old) TV and it would only play them in B/W.
Check your VCR manual (or look up the specs online if you've lost the manual). Generally, VCRs sold in the UK can handle both PAL and NTSC. (Unlike American VCRs, which are usually NTSC-only.)