>> I would love to buy an Aloe Vera plant, but I cant seem to find a source of
> the Aloe Barbadensis Miller variety here in UK.
Well, this cactus nursery keeps A. barbadensis, which they also describe
as "Ugly boring long green leaves. Someone must like it!" haha. Dont
know which cultivar it is (I'm not sure it's important).
Also, I dont know how well it grows in your climate... all things you'll
have to investigate. Maybe you'll have to buy a greenhouse as well (: