I managed to fix it and I can get in the server now. If anyone else has the problem what worked for me was deleting the files from the Battle Eye folder in the Arma 3 directory then verifying my game on steam.
My internet is just fine and you still owe me a freddo you hobo.
If you want a good budget processor I would recommend something like an i5, you can get yourself a decent one for around £150. If your current processor is an AMD then you will most likely need a new motherboard for that too so you might be better of sticking with a new AMD processor for now...