Hotpoint FF175 on the blink?

Our Hotpoint FF 175B is over two years old and has generally worked OK. Recently however it has twice stopped working properly, the fan doesn't come on and it makes a loud clicking sound. When the door is opened the clicking slows down but doesn't stop and the light does not come on, though I think it does come on for a second or so and then goes off again.

Can anyone help? Hotpoint want to charge £100 to come out with no guarantee they can fix it. If I could work out how the door switch works I might try to fix it myself.

Thanks
John