i broke a fixed rate with Haven (EBS) to take a new, lower fixed rate, there was a break penalty for this. i understand with some banks, if sticking with the lender to go on to a higher rate than existing they will waiver the fee.
if you want to break to go to another provider there's a 99% chance there will be a fee.
Theres a formula for working out the fee but sorry, can;t remember what it is