Thanks - I hadn't realised there isn't even some minimal form you can submit and get generic responses on. I just tested the recovery process (https://accounts.google.com/signin/recovery).
If you don't have enough information for them to reset, Google just provide links to instructions to not be locked out in future, and to create a new account.
If you don't have enough information for them to reset, Google just provide links to instructions to not be locked out in future, and to create a new account.