Don't worry, I think the maths we did was only based on C3!! Our lectures were on a different topic though so I can't be sure
as for the sciences, I do maths and further maths (did chemistry at AS but dropped it) and I managed but I did struggle because knowledge of A2 chemistry or physics was definitely expected!! I think I only got away with my poor answer to my second question because of double maths 😂 Out of the four sciences and engineering questions, the first was a compulsory maths one and the other three were definitely based on chemistry and physics so I would look over that a bit too. Don't worry about swotting loads because it's not the sort of test you can revise for and just throw facts at them, it's more of a "can you apply scientific thinking to these situations" and on ours they intentionally talked about an area of science not covered by a level syllabuses so that we were on even ground. Yeah you can use the Internet which I found helpful in my minor question (cultures) because I was able to look up quotes from a book I was writing about, but I didn't use it in the other questions - there wasn't time!! Good luck and enjoy the day at UCL!! Are you going to firm them?
Sorry that's a long one!! Trying to give fair advice without giving too much away is harder than it sounds 😂😂 but I emailed in advance to ask about chemistry and physics because I don't do them so I don't feel too bad about it!!