Heyy! I'm also in yr 10 and have my mocks, starting form the first Wednesday back... 😶
(I'm not the best at english, so don't take my word fully)
english lang - I think the main thing is just to get yourself familiar with each question and how to structure your answers accordingly. Also something which I have found useful, is to look at grade 9, model answers to see what exactly I need to include to ensure top marks. Just another thing which was recommended to me was just to read a variety of texts in your own time, e.g, newspaper articles, letters etc and to just annotate them, just so you have a broadened knowledge of different texts.
english lit - (this is my weakest subject, so again don't take my word completely on this!!), but I say just learn quotes which can be used for multiple characters/themes, so that you don't need to learn as many. And for notes/context on poems and stuff, I highly recommend looking at the resources on physicsandmathstutor. Another technique that I personally have never tried, (but I know many people like doing) is mindmaps for each character/theme.
maths - I think the main thing for maths is just to do as many exam questions/past papers as possible as well as watching walkthroughs of papers on yt if you don't understand a question. Also if you notice you keep getting a specific topic wrong, you can practice it using mathsgenie, corbettmaths, or drfrost (if ur school has given you a login)
science - so I do triple science, so I'm not rlly sure about combined, but the main thing again is once you have learn and fully understood the content, just do past papers/exam q's as questions often tend to be repeated. sececa/cognito is good if you don't understand some of the content. Another way, is learning from the mark scheme , eg for biology you need to be very specific with particular answers, so by lookign at the mark scheme, you will know exactly how to word your answers.
geography - geography is very content heavy, so what I recommend is mindmaps/posters on case studies/fieldwork/key processes. Again doing exam questions is useful, but focus on the long answer essay questions. (I don't rlly have anything else for geo sryy!)
computer science - I think the main thing for cs is just to make sure you understand the key concepts fully and the theory behind it (especially for programming/coding). (again, idk what else really...)
I don't do the other subjects so I can't really give any advice on them.
(also pls excuse all the spelling mistakes lol!!)
Idk if this advice useful, but I hope it helps, even if it's just the slightest!!

edit: something i forgot to mention is that when your revising make sure you also have the specification handy (especially for science), to ensure your learning everything that you need to know, and not wasting time learning stuff you dont need 😀