The only thing I will add to that, is that the only sure way of repaying your mortgage, is obviously to go in on a repayment basis. I would do this if it becomes affordable.
An ISA is another way out, but your returns are not guarenteed. I also wouldn't speak to my bank about such an important matter, as banks are notorious for pushing their own products and often being overpriced and not giving the best returns.
Do some research on the internet, this site should help you in the first instance. Then, please ask any other questions http://www.google.com/cobrand?q=ISA&...www.fsa.gov.uk