You are correct: The Basic Skills Initial Assesment (BSAI) is to ascertain Literacy & Numeracy (L&N) skill levels against the national qualification framework.
If you have passed the basic Recruiting Test at your AFCO, you should pass the BSAI at Lympstone. In theory, if you pass PRMC, but fail to reach BSIA Entry level, your entry will be deferred until you reach the required standard.
To date, I personally haven't come across anyone failing to meet the basic entry level & having their entry date deferred.
The tests are just multiple choice on the computers in lympstone, i found them to be quite easy and i'm not a genius. You shouldn't have any trouble with them, the lady who runs the learning centre is really nice and helpful.
If i remember rightly a level 3.3 is acceptable, so you should be fine mate.
Thanks for replying. I get worried when I hear about doing maths and english tests, because I'm not very good at either of them. But I think I should be alright they dont sound to bad at all.
Thanks again lads, everyone is a great help.