I am not sure if its powerful enough but I have a compressor with 50 litre reservoir with in line filters and water traps etc I will need to check the psi on it. If that is powerful enough I could get the adapters and ask the diving instructor to teach me how to fill the tanks maybe.
Not only a matter of a compressor being up to the pressure (3000psi or 4500psi) but filtration must be up to breathing air standards
You need either a paintball or diving compressor - thousands of pounds
Dive shops can fill, but need a different fitting, many will fill for paintball but usually require the customer to bring the adaptor.
But why look for fills off site? It will cost you money which you don't need to spend as you can get air at sites and have enough to take home for any testing.
If on a budget then start off slowly - check the rest of the forum for advice, preferably get to a paintball shop or an event and cue k out their stalls.
Your main purchase is goggles, but you don't have to buy top of the range - just the ones that feel right to you
Then gun, air cylinder, hopper, pots, pod carrier etc
A cylinder does not have to be the most expensive, a 3000psi aluminium / steel will do you well at £40 or less