Hmm, more complications.
I've discovered, to my surprise, that whilst it's no longer possible to open a new free Google Apps account for my new domain, and I don't regard the paid equivalent as being good value, my existing google apps (free) account might allow me to add another domain to my account. Or at least what they call a 'subdomain' to my existing primary domain. I'd eat into my user allowance (ten users), but that doesn't worry me as so far I only have three.
Arguably, even if I can make it work, this could be a mistake... 'all my eggs in one basket' if google decide to change the T&C in some unpleasant way in future. But it may buy me some breathing space until the need arises for website hosting. And I must admit - the mailbox size limits (of the entry-level packages) does worry me wrt to the hosts discussed so far. Eric's was probably the best in that respect, but also not the cheapest - and my budget is definitely shoestring. In comparison I'll probably never use Google's 10GB so mail from the dawn of time can just stay on the servers, and if you trust google, big 'IF'
I know, everything is nice and safe and disaster-proof.
Another downside is Google don't seem to document bandwidth download limits, or penalties for exceeding them, for the free edition. But, from searching forums, there do seem to be some. This is a worry, but perhaps not a major one with my 3Mbps home download speed
I'll be looking into this further tomorrow.