Mmm this is a difficult one to answer reading through all the replies, first off i would like to point out that paintball is a genuine sport to many people not a weekend Rambo type thing.
Safety safety safety is the next thing that comes to mind. I work as a safety marshal at a site and have to be honest if you are this new then you shouldnt at all try and play alone / with friends etc. The idea behind this "outlaw" thing is presumably from something you have seen from the yanks? It might be worth pointing out here that these kind of days is what started paintball off all over the world, we have by far moved on from there and experinced and sensible people have wrote a set of rules or code of conduct making paintball a safe and enjoyable thing. It maybe worth mentioning here that going it alone has many many safety concerns, first off does anyone have a chrongraph? These little machines messure how many foot per second the marker (not gun) is shooting as legally you must shoot under 300fps, most masks are designed to withstand impacts of that mark and obviously have a safety factor but i have seen cracked lenses at that speed before and lets remember you only have 1 set of eyes! If you have looked on websites or whatever that try and promote things like this then chances are its some hillbilly / redneck type thing where there is no sites or anything for many hundreds of miles, in your case there will be many sites not so far away.
Next HPA or co2, how would you fill your marker? Without a shadow of dowt dont try and use anything changed to 3000+psi if you dont know what your doing, common sence says its not worth blowing yourself and others up!
Next the 300 balls in a day... personally i love to shoot paint so cant really answer this the best, however there is many walk ons that cater for pump players, i have played against pump players before and they get a real enjoyment out of 1 shot 1 kill etc maybe have a google up on walk ons within your area that cater for such things? Also worth noting here you can buy your own pump really cheap (i bought a couple a while ago and although i havent used them they were really cheap, i think i payed about £20 each or something).
There are many sites now that incorporate walk on fee with the paint they sell so £35 for a box a paint and thats including your entry fee (i know my local site does this), if you dont think you will shoot that many sell them to a friend or just keep hold of them maybe you might get a chance to lend a electro marker at some people and just feel like hosing the place down (try it you will love it lol)?
I think the last question you want to ask yourself... how would i feel if a mate lost his eye because i decided to try and go it alone? Or how how would you feel if it happened to you?
My guess here is you are considering asking people from your TA to join you and try and play snipers or whatever in a woods somewhere? 1st thing i would do is speak to CO and anyone with common sense will say dont do it, of course by you not following what he / she says then maybe the army or TA is not for you? Of course the other option would be to express this interest to your CO and see if he could arrange something for or with you for the lads, you never know they might want to take you lot on and see who the real know it alls is. I am sure there will be sites who respect the work that our lads do and offer some kind of group discount or incentive?
Cant think of a great deal else to say on the subject but a question you should ask yourself, would you try and arrange some kind of rally in a car with mates when you havent passed your driving test? Course not, lets hope common sense prevails