sullen - 8:13 am on Jul 12, 2005 (gmt 0)

.ac.uk domains have to be registered with UKERNA. If you are a hosting company, you can apply for an account, or you can use any of the providers listed on ja.net (in the connections>domains section).

Yes there are restrictions, in that the domain has to be registered to a publically funded educational establishment, a research institution or a "Learned Society". Full eligibility guidelines are on ja.net