I have seen a few companies advertise internships positions, for example Lionhead, etc, but I have not notice many intern positionsaround the UK. I know companies would have vacancies but not advertise them or they mainly looking for experienced staff rather than someone who would only stay there for a few months. I would be looking for a games design intern or support intern. I had a support intern interview last year with marmalade. I think the best way to look for them would be to get to know one or two people in a particular company I would like to work for.