I would like to opt out(well check if I am opted in) to BT FON. Though it asks for a bt email address, which I didnt have. So I created one, then tried to check status or register at https://www.bt.com/wifi/secure/index.do?s_cid=con_FURL_btfon though it says my user is invalid. The user I just created and can log in fine to. Does this take awhile to reflect across all the services? Also can I not just opt out/check status without this bt email address?
It needs to be the primary email address that should have been created when you first signed up to BT Broadband.
For new customers, I would expect that to be the same as your BT ID (the one you use to log in to MyBT on this web site), but BT have over-complicated things recently, so there seem to be all sorts of strange special cases.
For older customers on BT Yahoo mail, it's the email and password that you use to log in to BT Yahoo mail.