Go to the Classics page for each university and look under ‘Entry Requirements’. Most of these unis will specify what they want from US students. When APs are not directly stated, you can work out A* = 5, A = 4 and so on from the required A Level grades.
Usually 3 x APs grades will be needed. Not all APs are considered equal, however, and I have a feeling that Human Geog and Psych may be not be counted as full APs, esp for Oxbridge. But you will need to check with each uni and Classics department.
Oxford Uni also says this
“Candidates should normally have Latin and/or Greek to A-level, Advanced Higher, Higher Level in the IB or equivalent.”
Have you studied Latin? It looks like you need AP Latin. Check all the uni websites regarding the Latin/Green requirements.
If you have yet to take the AP tests then your place will be conditional on you achieving the grades the university asks for. If you don’t achieve them, then the place may be revoked - yes this happens.
If you apply during your gap year, you will have the scores in hand