Use Karl Jeacle's mortgage calculator to get a good idea of the monthly repayment, total interest costs, amortisation of the mortgage etc. The exact amount may differ depending on how the lender calculates things but it should be close enough if not exact in most cases. Note that it does not factor in owner occupier mortgage interest tax relief (at source these days) or additional monthly costs such as mortgage protection life assurance, home insurance (if paid monthly) etc. Karl licenses the calculator for use on third party sites so contact him if you're interested.
Thanks for that info.
What I would like to know is if anyone knows exactly how the financial institutions calculate these repayments as I need to code this into a couple of sites..