There's a couple of blokes in a really really big truck that were at the 2k2 events and the Midland Masters who test HSE bottles. It costs £20 plus Vat and they can either take it away at one tournament and bring it back tested at the next or they'll post it back to you within a week.
The company, I think, is H-Pac - they sign in as airforce1 on these forums i think.
i dropped my bottle off with them for re-test at Kennys at had it posted back to me within a couple of weeks at a cost of about £30 for everything. Excellent service and thoroughly recommended.