If that fails try giving Andy Kearsey a ring at Target Tools and Equipment. Andy is based in Gloucester but has a few distributors around the UK.He does a deal where you hire a bottle that costs around £50 for 3 years, there is a refundable deposit of around £30 and then around £25 per refill. His number is 01452 739005 or email
targetgas@blueyonder.co.uk. Can supply Argon/Co2 or straight argon as I get for Tig welding.