How can I fix my hotpoint WM52 door catch?

I've got a hotpoint First Edition 1000 WM52 washing machine, and the door will not close (I've not used it before, as it's in a new house).
Could this be a problem with the catch, or would it most likely be the interlock?
The front part of the catch (a white plate) appears to be cracked, but not on the actual part that would secure the door.
How easy are either of those (interlock or catch) to change?

Many thanks :)