How to choose the 5 universities

You would have to submit all 5 choices in October as far as I know. You should consider the cost of living if that is an issue for you (if you want to go to LSE or anywhere in London), you should look at employment and earnings after each course, you should go to open days and see if you like the 'feel' of the place. Also, check the different courses to see if it is what you would like (some may be more mathematical than other). Other than that, I am not really sure.

The OP is correct in saying that UCAS applications can be submitted in stages - Cambridge by Oct 15th and the rest later.

Ok, I was not aware of that. Thanks.