High School Student Help in the UK

My daughter is about to marry an UK citizen and has 16 year old child who has not completed high school in the states. How do we find out more information on how and where he needs to go to school as we were told that the six form schools in our future area are completely full. We do not want to have any lapse in his education, but we are not sure where to go. Any suggestions?

Where will they be moving to? I'd start with contacting the local authority (like municipality). At 16, kids here will be finshed their GCSEs and going onto A levels, usually.

To find the right local authority:
http://www.direct.gov.uk/en/Dl1/Directories/Localcouncils/index.htm

Education information post 16 years of age:
http://www.direct.gov.uk/en/EducationAndLearning/14To19/OptionsAt16/DG_066261