Sorry for the delay in responding - I've been away and my phone died, so no internet access
Having done a bit more looking around, a Kobo Vox is looking less likely. I'll probably wait until I can get a tablet running Android 4, by a known name, for £100. Right now I could get two of those three, so I figure I should be able to get all three fairly soon, and I'm not in a great hurry.