bitcoins themselves no. not unless a single bitcoin was valued at £6k each (look into assets on HMRC)
EDIT: bitcoins themselves do not have VAT on them, much like swapping pounds for dollars or euros. however capital gains would need to be paid if bitcoins exceeded £6k per coin.
http://www.hmrc.gov.uk/cgt/possessions/basics.htm#2and income tax on any profit you make when cashing out your bitcoins back into pound coins
but if your a business selling products and the products are VAT rateable. then price them in bitcoins at the pound rate inc VAT. and when you cash out the bitcoin, pay the VAT to hmrc.
EG
sell a TV
EX VAT =£560
INC VAT =£700
sell for bitcoin at 10BTC (£700 current value)
cash out bitcoins and pay £140 VAT.