Can we ask how non-facilitating your DC's possible A level choices actually are op ?
Cambridge Subject Matters seems to include a fair number of options
Choosing subject combinations that genuinely keep your options open is trickier than you might think. We often encounter students who have chosen to take two arts and two science subjects at AS Level because they believe it will keep their options open. While such a subject combination does provide a suitable preparation for many arts and social science courses at the University it can make you a less competitive applicant for Cambridge’s broad-based science courses.
There are certain A Level subjects that are considered either essential or useful for a number of courses at Cambridge, therefore choosing one or more of these will help keep your higher education options open. These subjects include: Chemistry, English Literature, History, languages, Mathematics and Physics. Other subjects that also facilitate course choice at Cambridge include Further Mathematics and Biology.
If you want to keep your options open but you think you are likely to want to study an arts/social science or science-based course at university please read our further advice overleaf.
Are you inclined towards the arts or social sciences?
If you think you would like to study an arts or social sciences course at university but you are not sure which one, then English Literature†, History, languages and Mathematics are good ‘keystone’ subjects:choosing one or more of these will provide a good foundation for your subject combination
Other good choices to combine these subjects with include: an additional language, Ancient History,Classical Civilisation, Economics, Further Mathematics, Geography, Philosophy, Religious Studies and sciences Biology, Chemistry or Physics.
Other possible subject choices, for instance Archaeology, Citizenship, English Language, Environmental Science, Government and Politics, History of Art, Law, Music, Psychology or Sociology, are useful preparation for some of our arts and social sciences courses
www.kings.cam.ac.uk/files/undergraduate/subject-matters.pdf