As @howful says, you are required to put ALL standardized testing scores on the UCAS form.
For Oxford, you must have at least 3 scores of 5 on APs. For PPE, it’s helpful to have a math and essay-based (eg, History, English) exams. In theory, if you have enough 5s to meet the requirements, your other scores don’t matter, but PPE is an extremely competitive course and these are relevant subjects.
If possible, instead of you noting that you self-studied for the APs, it would be better for the person writing your recommendation to note that your school does not offer those classes and does not offer APs, and it is a measure of your interest that you self-studied for them. Tbh, though, lots of students self-study for APs w/out having the class.
Obviously, it’s not wonderful to have low scores in relevant APs (esp. Comp Gov, which only counts as 1/2 an AP, but actually is really useful to the first year Politics module!), but if you really nail the Thinking Skills Assessment (TSA) test, it could work out.