From my point of view, physics is really difficult or is considered one of the most difficult A levels just because the content is extremely difficult to grasp. IF you come across something in level A physics, especially A2.You have to accept that it happens even though it doesn't make much sense. It's not difficult if you can rearrange equations and you're good at mathematics. They give you a giant leaf that you can take to the exam with LOTS of equations.
To conclude, getting an A in physics at level A is not difficult. You must first have the interest, a solid foundation to build, be disciplined and increase your efforts by enrolling in physics tuition with an excellent A-level physics tutor. To study any subject at A-levels, at least five GCSE subjects are required with at least a 4 (or C) in each of those subjects. Similarly, the minimum requirements for studying Level A Physics, as set by most universities, are a 6 in GCSE Maths and GCSE Combined Science or Triple Science and a 5 in GCSE English.
Level A physics will allow you to feel more comfortable researching and analyzing the different aspects of the natural and physical world. It's a big jump from GCSE as are all A-levels, but as long as you're good with numbers and aren't particularly stupid, it's very doable. Well, it depends on what your strengths are and what subjects you're currently studying in Level A Physics. Grading limits may seem low at first, but tough examiner grades and complicated questions make getting good grades in Level A Physics a real challenge.
In addition, when you study Level A Physics, your teachers (and your exams) automatically assume that you can remember and reuse all the previous physics knowledge you have learned at the GCSE level. Therefore, according to pass rates (more details here), level A physics is more difficult than average A level. I got an A* in physics from GCSE, but I realized almost as soon as I started Level A that that counted a lot in comparison. Many people argue that Level A Biology is a much bigger step forward in terms of the actual amount you have to learn from GCSE.
If you have successfully passed O levels and are thinking about pursuing physics at Level A, get ready to learn more about electric currents, magnetism, waves and infinitesimal particles.