The websites are clear thanks. After following the usual chain of phone numbers in British bureaucracy it sounds like the EHIC would be useful as long as you don't intend to be resident here. It sounds to me like a straight replacement for the E111.

If you are intending to work then i think you can get up to several years cover with a 'Residual E106' if you have contributed enough National Insurance in the last 3 tax years. This may be acceptable in place the most basic of private paid Swiss insurance. There is also a 'non-working E106' and an E101 for people who are working but i'm not so sure about those.