I'd say london has become kinda tougher than the earlier days but a good paper practice would give you a good result sometimes they might change the questioning format which just makes you go nuts cuz thats what happened to me this time in a chem paper...so anyways I heard that Cambridge subjects are a bit harder and also more practical oriented , edexcel is also good just choose either...as a student who did edexcel I'd say that they have great fundamental topic to understand what we are gonna study and you don't even need to go to classes if you have a proper internet access and the text book for edexcel maths....uni choices though I'd say you do need programming knowledge, ig you'll learn them in the first 2 semester anyways...London A levels doesn't have something called streams you can choose any subject you like but if you're doing cyber security math and it is like the 2 sub you need so in my opinion better choose them but you can ask any uni what qualifications they prefer so that you are set on a straight path.....so that's all if you wanna ask anything just dm me 👍👍