In that case, if you want to wait, go for it, but Clearing options will be restricted this time next week. They may well accept you without the GCSE, but it's by no means something to hope on, especially if they've told you they'll reject you without it.
Do you have any other unis in mind? Have a look at
http://clearing.telegraph.co.uk/ to see if anything takes your fancy.
Best of luck and let us know how you get on