hii,
Im also a Muslim and did my GCSE's last year,
please know that GCSE's aren't everything and even in the future they look at any excentuating circumstances you had while taking them
I'd recommend Seneca (it has most subjects) or freesciencelessons on yt because its way easier to learn on that site rather than write like 70 pages
Constant revision truely doesn't guarentee good grades- instead try and find the structure to answering questions
eg English Literature to get above a 7, normally you should talk about tone, contrasting themes, shifts in perspective of a narrator (does he talk about an object then focus on a person?) symbolism, metaphors, personifiation and effects of language overall
History- always talk about long term and short term impacts, limitations in of an argument, tone of a source linking it back to knowledge and (though not always needed) dates for the events
Maths- Maths Tutor on yt
In terms of fasting, I'd recommend having food with a lot of protien to help you through the day (ie eggs oatmeal) and water as it can keep you more energised
It is possible to move from 5's to 8's (that happened to me in history till i leant that structure the month before)
Prayers- do them as soon as the azan calls and use them as a time for a break
Inshallah the exams go well for you and I wish you the best