The UK angle is unique, and if they require AP scores, then you need to provide AP scores. The HS does not offer APs? Self study. The AP course is taught in the Fall, but the exam is on May? Review (or revise in the UK lexicon) in the Spring.
Much like studying at UK unis, there is no hand holding in the application process. They want what they want and it is up to the applicants to figure it out.