bitcoins from 3 different accountants i seen, class bitcoins as a personal possession(asset) not a corporate product where you can claim back VAT and all the blah. not a raw material (commodity). not a division of a percentage of ownership of a company(share). its a personal possession asset.
a personal asset, much like antiques, cars, jewellery and art. the only thing with it is that with any personal possession, even your TV if you hold enough of them and keep buying from one person to sell onto another day in day out, you would be classed as a trader.
if your interested in a starting point guide to your tax liabilities or freedoms
https://bitcointalksearch.org/topic/uk-tax-in-relation-to-bitcoin-143425