You don't say which FTTC provider.
For BT Infinity, a username 'firstname.lastname@example.org' will work (so will many other usernames, that is the default the HomeHub uses).
It does not require a password. Some hubs won't accept an empty one, I'm not sure whether a Win7 pppoe connection requires one. Anyway, Infinity is not fussy, if you have to give a password, anything will do (people suggest 'BT', but doesn't matter).
Moved (with trepidation) to BT Infinity 2 for upload speed. Happy BE user for several years.