The flap was broken by my son when washing it. Are the flaps easy to replace. I think ebay sell these flaps (WHALE) for around £6.50
Hoping its easier to replace than the complete assembly.
Someone asked a question very similar only a few weeks ago as one of their water pump housing hinges had broken. I said that you would need to replace the whole unit as one but someone proved me wrong as you can actually buy the flap and hinges which obviously I didn't know about at the time.
I managed to locate the thread so you need to read the post from 'birdman101' who provided the link both for the flap and hinges.