@Slippersandshakes
This thread interests me because my DS will be picking A-levels in 6 months or so and he has no idea, apart from not Eng Lang. He could choose any of the 9 others he's doing plus 4/5 that are new at A-level or weren't chosen at GCSE.
I'm going to go through a similar process (and I will share in due course, if it helps others).
In your case, starting with Trinity College Cambridge link
It suggests 'generally a good idea to be taking at least two A levels that give you a good general grounding in a field of knowledge.' and 'If you are interested in arts and humanities, then taking two out of English Literature, History, Geography, a language, a Sciences subject and Maths is usually a good idea.'.
But 'these are not eligibility requirements for admission to this College, and we will consider seriously applicants who are high-achieving but not taking a combination as listed' (would be happier if they said 'equally consider'!).
There are subject combinations for some degrees, obviously, e.g. 'English: applicants need to take either English Literature or combined English Language and Literature at A-level.'.
But, there doesn't appear to be a general accepted/not accepted list.
Looking at the Philosophy course, as you mention it as a possible, then -
'No one A-level subject is a prerequisite for those hoping to study Philosophy at Trinity. Entrants in recent years have arrived with A-levels in Biology, Chemistry, English, French, German, Greek, History, Latin, Mathematics, Music, Physics, and Religious Studies. Some also take A-level Philosophy but it is not essential. The only essentials are a wish to get to the bottom of things and an ability to think long, hard, and clear in doing so.'.
So, short answer, there, the combo is ok (for courses that don't require a specific subject).
Other Unis, obviously, have different lists/criteria, so as mentioned before it will be a matter of trawling through data to get a better picture.
On the Bristol website, they have a list of subjects which meet their criteria of (as they call them) essay-based subject, maths-related subject or science subject. Both Drama and RS qualify as 'essay based'.
On the Leeds website I couldn't find anything re general subjects apart from General Studies and Critical Thinking being excluded.