I'll try to answer both your questions together. Firstly, Sport Science is exactly what the name implies, i.e. it's a science. Therefore, universities generally expect candidates to have at least one A-level in a science subject. (Some specify Human Biology or a similar subject). For typical entry requirements, see here:
http://www.smuc.ac.uk/Courses/Undergraduate/Sp ort-science/index.htm
Sport Science is an excellent basis for primary teaching. Primary schools like classroom teachers to take on additional responsibilities within specific subject areas. While a degree in, say, Ancient Greek wouldn't prevent someone training to become a teacher, it wouldn't stand out on their c.v. as something which would be useful in a school environment. However, every primary school wants to have a PE specialist on their staff; a Sport Science degree would be seen as a relevant qualification.
These links might also be of interest to you:
http://www.bases.org.uk/
http://www.learndirect-advice.co.uk/helpwithyo urcareer/jobprofiles/profiles/profile820/
http://www.tda.gov.uk/
Chris