The other tip is that they're more likely to be helpful if you don't leave it all until the end of January
Yes I try and remember that each year along with putting money aside for the actual bill each month but never quite manage it.
Last year their online system was down over the last few days of Jan and I think they ended up giving peope a bit of extra time as a result but hopefully mine will be in by close of play tomorrow.
Plus when I first signed up you had to have a password snail mailed to you, so you need to leave enough time for that process too if its still the same.