Guysss

It depends on the sixth form / college - i believe most want at least a 6 or 6-6 for A Level for sciences (i think, cant rmbr) and (definitely) a 7 in maths.
For science a level, it doesn't matter if you do double or triple, as long as you get the grades
try convincing teachers to put you up to higher level, if they want you to better, use cognitoedu.org and past papers (sciences), and corbett maths, maths genie and past papers (maths)

They told me if I will be give grade 5 in maths and science mock exams in October and November I will be move up
But English is my second language and I came to UK 4 months ago

Grind past papers and cognito for sciences, and grind questions on ur weakest topics in maths (past papers too ofc, especially higher)
For maths, always try to hit the last half of the papers since they are always the hardest, but always nail the first half since that means you get at least a 4.
For Edexcel exam board, the last half of foundation is the first half of higher paper (it might be the same for other exam boards, idk). When u get into higher, keep constantly revising the easy parts few times a week, but try he grades 7-9 exam questions on maths genie website