The main student groups affliated to the political parties in the UK are -
Labour: http://www.labourstudents.co.uk/
Conservative: http://www.conservativefuture2007.blogspot.com/
Liberal Democrat: http://www.libdems.org.uk/party/liberal-youth-226022
One major difference between student activity in the UK and the USA this autumn/fall - is the emphasis on voter registration. While US students will be encouraged to register for the coming elections - this is a less stressed aspect of British student activity. All households (including student households) are required by law to register all persons aged over 18. Sadly many students miss out on filling the forms - and so can't vote. If you are a student at university, get in touch with the Electoral Registration Officer at the local council.