tosh.....
Further to previous, if you are looking for a once in a lifetime e-mail address, to last a lifetime, then you need to be looking at '1&1' - or similar - who will be registering a
standard '.co.uk' address for you with
Nominet, the UK equivalent of the DVLC for UK domain names, or likewise
ICANN for international '.net/.com'. ...Any alternative name that is somehow ISP related within the name (e.g. above), however detatched or allegedly free from their standard ISP service, will only be around as long as they are; and of course some wont, be it 5 years, 10 or 20. ...That said, some ISP's do act as agents, like '1&1', to register you a
standard address with Nominet/ICANN.
So you might say what happens if '1&1' - or similar - go down the pan. ...It doesn't matter, they are merely agents; you are registered with the .uk (or international) domain name authority.