Fish circulatory system 😭 I've never heard of that but then again we probably do different boards I do Edexcel.
Biology Paper 1: Just pull out PMT questions and work through every single one of them for every topic. Make sure to carefully look at the mark scheme because you'll almost ALWAYS find the pattern for the answers they want on some questions. Mark schemes are your best friends + practice papers. Do past papers as well and again look at the mark scheme carefully, especially the questions you got wrong. Note them down and if you have a textbook visit the topic and UNDERSTAND it or watch videos and practice questions again.
I can't help you with Chemistry BECAUSE I AM FAILINGGGG THAT SO BAD.
Physics is just a bunch of PMT and past paper questions TRUST ME! Physics is the subject where you have to apply knowledge just like math more than other subjects so focus on practice questions and watch videos on topic you don't understand.
I don't do Geography so I can't help you there and I'm absolutely FAILING history so there's no help there either.
English Language: Past papers. That's it. Just a bunch of past papers and pulling out the most ambitious vocab possible in Section B of both papers while making sure the sentence makes sense. ALSO TIMING. PRACTICE UNDER TIMED CONDITIONS. get your teacher to mark your papers.
English Literature: Same as language but vocab isn't very important. instead you need to know those fancy words specifically related to your texts. for example, macbeth has a hamartia (fatal flaw) which is ambition. stuff like that. PRACTICE PAST + PREDICTED QUESTIONS UNDER TIMED CONDITIONS. even make up your own questions. get your teacher to mark them. focus on the feedback. nail down your language + structural techniques and your essay structure. DON'T USE QUOTES + CONTEXT UNRELATED TO THE QUESTION. examiners hate that.
modern languages (i do french)... i might get a U in this but my writing and speaking exams will probably save me and get me a 2 instead so i'm not the best person to ask for help there.
math is just practice questions. that's it. pull out corbettmaths, mathsgenie, firstclassmaths. anything. JUST PRACTICE.
and yeah i get you one of my exams is 5 days after everyone else finishes but thankfully i have 1 friend who does the subject too and there's another subject that's being tested on that day and another one of my friends does that so i have them too so i'll have 2 friends that day but i wouldn't worry because you can always make plans in the summer!
and results day... YEAH I GET YOU MAN MY FRIENDS ARE SO SMART there's no way i'll open my results with them but if you put in as much effort as possible right now you can still get good grades.
good luck!