Sorry, this might be a bit of a dumb question, but can I apply for a 3 or 5 year GT visa if my passport expires in 2 years? Is it possible that in two years I will have to redo the visa application again?
You just need a passport with up to six month validity. You will only get three months visa. When you arrive the UK, you will get a Biometric residence permit. You can renew your passport in the UK.