@MJMooney - I use Android on a cheap PAYG deal, and it is definitely do-able with a bit of tweaking. Hopefully your visit to Orange sorted you out, but if not, I think you just need to get a couple of useful widgets on your home screens.
It sounds like everything you're downloading is going through your 3G data connection and using up internet usage data. (That might be intentional on your part..? In which case ignore me.) But if you've got wi-fi network at home/work(both?) then you can cut out a lot of data charge by setting your phone to use the wireless networks you're commonly in range of and switching off 3g data connectivity. This does rely on you having wifi - so may or may not be of use to you.
My phone's setup to use my wireless network at home, and a number of other locations where I might have access to wireless. (My folks, my in-laws, the office, Hatton Country World...) Then put a widget on your home screen called "Data Traffic". It gives you a really easy, one-touch way to enable or disable mobile data connections, without effecting your wi-fi connectivity.
So basically, I leave my data connection switched off, and when browsing t'Internet or using email etc on my smartphone it routes through wi-fi. This won't be any charge to your mobile. And then if I'm out somewhere without wi-fi and I need to check email or suchlike, only then do I enable data connection. (And once finished, disable it again.)
So hang in there a bit longer - it may well be that with a bit of tweaking you can find a way to make it work for you on PAYG.