I just did it and it's not as hard as people think it is. I did OCR gateway I had a total of 6 exams (3 units for each exam) and 3 sets of coursework. It is an extra 2 units for each of the sciences which i enjoyed more than the other units because it was ACTUAL SCIENCE ( for example, in chemistry we learnt about moles). I found the coursework a lot harder than the exam , i even had to retake my bio coursework during exams (was sooo pissed off). To be honest i didn't really revise that much in year 10 (big mistake) which meant i had to catch up a lot in year 11. Make sure you revise well for your mocks and topic tests because although it's not the real thing it will help you remember a lot of the information. Science GCSE is really just about memorisation so make sure you get a CGP and memorise that book ( i literally memorised word for word) and do plenty of past papers (do them all but not too early, save them for exam season). Being the idiot i am, i left my revision for the actual exams till the last minute (like literally one day before) and had to cram everything in one day (which i don't recommend , pls start early) . Also the exams were quite close together ( like 3 exams in a week). It may seem difficult but trust me anyone can do it. I got A* in chem, A* in physics, A in bio (getting remarked cuz i am one mark off)