Oxford considers grades and attainment in context, including school and neighbourhood information, care experience, free school meal indicators and other widening-participation data where available. For Materials Science, departmental admissions materials state that UCAS grades, contextual information and mitigating circumstances are considered during selection.
Oxford Materials tutors recognise that many school students have not studied Materials Science as a named subject. Applicants are not expected to arrive with specialist undergraduate-level knowledge, but they should show strong Mathematics and Physics foundations and curiosity about how materials behave.
If your school limited access to Chemistry, Further Mathematics or relevant enrichment, explain the constraint through the UCAS reference or extenuating-circumstances route rather than relying on the personal statement alone. Evidence of curiosity, sustained problem-solving and reasoning from physical-science principles is likely to be more useful than a long list of unrelated activities.