They don't send anything by post during the application process, but when you receive email invitations to the various stages they list the contact details they have for oyu on the bottom. They give you a number or email to use if they aren't correct. I think it's the bog standard HR one though, so it might be worth sending an email to them with as much detail as possible; your name, DOB, when you applied etc and informing them of your change of address.