I've tried to list the more neutral sites, (ie. those not associated with a particular religious belief or methodology), however some may slant towards a particular style or viewpoint of home education.
Some will give guidelines about the law, others may offer useful resources or information, or be of interest to those with SEN children. Check out a few. There is no right way to home educate. We all do it differently.
A Little Bit of Structure - forum and support for parents who use a little - or a bit more - structure in their home education.
Education Otherwise - UK charity offering information, advice and resources to home educating families.
Home Education in the UK Info and links
Freedom in Education (currently, Jan 2012, being revamped, so some links may be unavailable).
Home Education UK
Home Education in Northern Ireland
Home Education in Scotland (Schoolhouse)
Oxfordshire Home Educators
Dare To Know - a home ed blog concerned with home ed news and national legal concerns