Around this time every year I get asked by year 9 students questions like, "is physics hard?" or "do I have to be good at maths to study physics?". The first and simple answer is that currently you will have to study science in some form or another in the UK up to and including year 11. The choice of course however is very important for your success in science, and I think you should discuss with your own teachers which is the right and most appropriate course of study for you.
Generally speaking however science GCSE's are demanding both in terms of volume, content, concepts and ideas. Many of the ideas, you will have never come across before and the language will be new and can be quite complex. Whether physics, chemistry or biology is "hard" or the "most difficult GCSE's" is a matter of personal preference or opinion. More importantly your willingness to try, be resilient, listen and your own natural curiosity will determine your success. If you are willing to put in the effort and listen to your teachers, I am sure you would do well.
Do you need to be good at maths to study physics? This is a common question I get asked and the simple answer would be it helps if you like and are good at maths for sure. However at GCSE level I do believe with perseverance you can acquire the mathematics skills needed, and the best thing to do is practice, practice, practice.
In conclusion, science GCSE's are not easy but they are fun, interesting, demanding and will inspire you, if you are open to trying and doing your best. If you are thinking about doing a single GCSE in Physics at higher level you will need to be good at Maths but, usually students who study these courses are thinking of studying the sciences, and maths at A level. Saying this many schools and colleges allow students to study A level sciences if they did the double award (award of 2 grades in science) as long as the grades achieved meet the school or college requirements.
My final thought is, you have to study science until the end of year 11, so you may as well do the very best you can, try and enjoy the subject otherwise it will be a very long 2 years!