Salam
Masha'Allah, you already appear so focused. Insha'Allah, you will go on to achieve your dreams.
However, why stop at GCSE, why not study further the sciences & use the knowledge with Islamic knowledge to guide the non-believers towards the right path. You will be a stronger muslim because you will more properly realise that whatever science says with affirmation, it is totally in accordance with The Quran.
That way, Insha'Allah, all the muslims can learn from you, would that not be amazing?
WaAliekum Assalam