I'm currently surveying all LAs in England and posting redacted responses to Freedom of Information requests on the web here
edyourself.org/articles/examcentresurvey2011.php
This is an overview from the first 116 (out of 152) responses
Schools have no responsibility towards children and young people who are not registered pupils. Maintained schools may be open to persuasion but Academies are outside local Council control. Local Councils have no duty to help children in elective home education and no power to direct schools to accept private candidates, and 17% of Councils take the position that they can fulfil their statutory responsibilities by doing nothing. 4% of Councils are not aware of the problem, possibly because they have very few home educated children, since Council numbers vary between 6 and 600+ home educated children. 15% of Councils keep a list of schools which take private candidates and a further 15% of Councils while offering only limited help at present, acknowledge the problem and would like to do more in future.
14% of Councils work hard to build bridges with local schools for the benefit of all home educated children but 36% still prefer to try and help families on an individual basis. 12% of Councils signpost families to the information for private candidates held by awarding bodies such as AQA and Edexcel though some Councils rightly point out that lists of exam centres should be treated with caution since some schools do not take - or want to take - private candidates.
15% of Councils have taken an alternative route and are using their own Pupil Referral Units as exam centres for home educated children. 17% of Councils tell families to ask local schools and 7% signpost to FE colleges. Only 3% of Councils told me that they tried to find suitable schools without success. Cutbacks have been cited, together with funding offered but not delivered.
The difficulty of arranging supervision for controlled assessments has only been acknowledged by 7% of Councils (who may signpost families to IGCSEs) yet this issue presents a significant stumbling block for private candidates who do not have a relationship with the exam centre. Home educators consistently identify peer support as a major factor, but only 4% of Councils signpost to home education support organisations and networks (both local and national) for information and support regarding exams. Councils have not mentioned the issue of access arrangements, yet this can be a significant factor for candidates with special needs including those on the autistic spectrum, who will have difficulties with unfamiliar surroundings, extended travel or large exam halls.