It's odd that we've never put ourselves on this list, maybe we haven't seen it before!
http://www.rabbitresidence.org.uk/ do Holiday Boarding in a variety of options, from aviaries, sheds, large hutches, special needs units (huge dog kennel buildings) even the manager's office when available. I believe the prices on the website haven't updated yet, we did up them slightly on Jan 1st. We primarily board for rabbits, although we have been rarely known to holiday board guinea-pigs if someone has come to us to board their rabbits as well.
We are near Royston, Hertfordshire.