Depending on where you are going it may be easier to use a 10l aluminium cylinder as a backup. It saves the airline faff.Thanks for the advice people. As for traveling (flying) with the 13cf, I'm right in thinking I'm going to have to remove the valve even if it's in hand luggage right?
The sling from AP looks a lot like the homemade one...
Alternatively, join a club and go diving in the UK. There will be some pony users to quiz.