Which type of course are you on? Ask for training at 6G level, then progress to 6GR.
6g etc are just welding postions, 6gr typically applies more to structural work (T, K and Y branch joints) and they qualify you to weld in 'more directions' with less tests as pipe inclined to 45* has aspects of overhead, horizontal and vertical. At the 'basic' end of the scale there's things like BS4872 which doesn't need a welding procedure i.e. you just need to produce the goods as opposed to working within a qualified procedure. ASME 9 and/or en287 apply to pressure vessels/pipework, power stations/boiler work, offshore etc and would be useless for aerospace work that'd be BCAR a8-10 and/or AWS D17.1
All of the above have various restrictions based on the dia and wall thickness of the test piece as well as multiple welding processes and material groups
As said, for now just get as much training and experience as you can get and deal with specific codings as and when you need 'em
Pretty pointless taking the tests unless your self employed and require them. If a company needs you to have the code then they will pay for it. Personally I would try to get into a job after your training do a couple of years gain some proper experience then go onto looking for the jobs that want people who can pass the tests. also the coding only last two years before they run out so you may fork out all that money just two waste it