There is no Oxford admissions test for History and Modern Languages for 2027 entry. Oxford's admissions-test page states that the tested courses in the 2026 application cycle are those using ESAT, TARA or TMUA, and that no other Oxford undergraduate course has an admissions test.
This means applicants should not prepare for the old MLAT as though it were still required for this joint school. The official course page also says Modern Languages written work is no longer required. The written-work requirement that remains is the History piece.
Preparation should focus on language competence, literary/cultural curiosity, historical reading, the submitted History essay and interview discussion. For post-A-level languages, expect tutors to be interested in your oral competence and ability to think about texts or cultural material in or around the language.
Sources: Oxford admissions tests, Oxford History and Modern Languages course page, Faculty of History written work guidance.