Hi Warwick student here, I have taken Maths, Further Maths, Computer Science and Physics and have the following advice: At the end of the day all universities are looking for (especially in fields like physics, engineering etc) are students with a great grasp of mathematical thinking who would be taught well.
Here is the important part: The more advanced maths you do, the better your mathematical analysis/thinking will be. While these universities won't give you tests with fm content, they would look for a candidate who can solve hard problems correctly as quick as possible, while showing that you can be taught by listening to your interviewer's advice and guidance. In order to become good at that, the more "difficult maths" you do, the more familiar you will be with difficult problems and the more likely you will be to solve the problems given to you faster and better.
So bottom line, although it is not required it helps not only on your portfolio but on the actual skills you gain from it. Best of luck!