If you can dig out your mortgage offer for the fixed rate, it will show what rate you would be on if you jumped off the fixed rate.

From there, it will aslo show the penalty you will be hit with.

You need to calculate if it's worth it - Phone Nationwide and ask for figures.

If you need advice, see a broker - you may get charged a fee since there is no fee earning opportunity for the broker.

Watch out for any steps down in the penalties - mine for instnace halve at the end on April 2009 - I'll wait until then before switching my rate.

Hope that helps

Adrian