Hope you don't mind me gate crashing your thread Vmax, but after you told me about the gas bottle today i found this place. Alot more expensive than you pal, but its hard stuff to get
http://www.weldinggases.co.uk/
They do pure argon, argon 5, Co2 Etc
20ltr Argon 5 charged to 200 bar. £80 deposit, £50 to fill. delivery £13. I've had straight Co2 from there before its £40 deposit, £15 to fill. Delivery £13.
Only posting cause i know how hard it is to get bottles rent free. They are based in Leigh, Lancashire if anyone is local for collection.
Cheers Will