If you are certain that you need to obtain this money as soon as possible, you will have to obtain advice from an Independetn Mortgage Advisor - try and find one via a recommendation as there are number of advisors out there and some are good and some are bad.
Due to the missed payments, as Luke said, if anyone will be prepared to help you then the rates would be high, and there may be high arrangement fees on it.
This may sound silly but it is always a first port of call - if you are now up to date with Virgin and there is no threat of courst action, try talking to them to see if they are prepared to help - you may be surprised.
With regards to your credit record - obtain the latest one available from Experian and take this to an advisor as this will give them the best indication of how you stand and what the options are - the score is not a guide, it is as Luke said, what it contains - so obtain a copy and see what it says!
Cheers!