Generally speaking, students in the UK apply for a single subject at a range of different universities.
Sometimes students become fixated by a particular university and so apply to lots of different subjects there, in the hope that this will increase there chances of getting an offer -
any offer - from that particular university.
Applying for a range of different subjects can be problematic because, as you say, it can be difficult to express your passion for the course when you also have to demonstrate your passion for
other courses at the same time!
I'd say you have a few options.
1. Decide which subject you'd
rather study, and apply for that subject only (at a range of different universities).
2. Look for joint honours courses which combine the different subjects in which you're interested, and apply for those. (For example, Actuarial Science with Economics, if such a thing exists.)
3. Continue with the approach you're taking, and try to express an interest in numbers, statistics, economics etc.
generally within your personal statement. The risk is obviously that this results in a weak personal statement.
4. Establish which universities pay little attention to the personal statement, and apply to those. (I've heard some say on open days that they have a policy of not using them for decision-making as the level of support which different students receive in writing them would make using them unfair.)
Good luck!
