hi I'm a welder fabricator by trade, I'm a coded tig welder and by my experiance tig welding ali is not something your going to pick up just like that its bad enough to learn on thick ali let alone 2 3mm ali.
before buying a tig set try and find somewhere where you can have a go and learn on thin gauge stainless where you can see what the malton pool is doing and how to control the torch and feeding the wirer in, cause like with everything not everyone can pick it up.
you'll need to rent a bottle of gas (argon) you can use it for (Dc) stainless, mild steel, brass and Ac ali you a can get half size bottle.
good luck