Hi MCaul.
Do you have a copy of your loan offer or agreement when you signed up to the 3 year fixed rate? If you do check this out . IIB would more than likely push you towards their tracker rates or variable rate.
Be warned that IIB have been submitting tracker rate offers that state that they can change at a months notice at their own descretion givin certain circumstance( if the euribor rate is more that 0.25% higher than the ECB for more than 30 days which would be the case) I have come across this and it has caused me serious problems. IT'S VERY MISLEADING.
It might be worth your while checking out the market place and compare rates as to what they are offering.
We changed our mortgage from variable to traker only last month and asked the questions...
Can we make extra payments if able? Yes
Can we switch to fixed? Yes
If we switch to a fixed rate, when its term is finished can we come back to the tacker? No a tracker rate is a one time offer
Can we move our mortgage to another bank on a tracker rate? Yes but thats only if they still have them as some banks are starting to phase them out
So unfortunately I dont think you will have a choice unless you are willing to change your mortgage provider.