The offer of no cap is hardly enough to warrant the evil of AOHell.....
Plusnet's Premier accounts are not capped as such (although if you start taking 150gb+ your likely to get contacted about it) what you need to do is figure out how much you actually use.
With 4 kids playing Xbox live or the computer online for most of the day I barely get to 6gb a month. Are you able to put a number to what bandwidth you want?
There are lite accounts that cost less.