Soldato
The hotel should allow you to move the booking without penalty.
HSBC do a flexi-loan
http://www.hsbc.co.uk/1/2/loans/flexible-loans
If you are a current account holder then you can apply online and if accepted have the cash in your account (or the ability to draw on it given it is a flexi loan) a few minutes later......if you have an account elsewhere it might be worth seeing if they have similar products or trying for the HSBC one anyway, it might takes bit longer to get the cash though.
