I don't do GSCEs as I live in Scotland. The system works like..
High school for year 1 - 2 fuck all.
High school year 3 - 4 Standard Grade (sometimes Int2s Int1s)
High school year 5 - 6 Highers(= to GSCEs), Int2s, Int1s and Advanced Highers.
I stopped after Standard grade with pretty good grades, and went to straight to college where I did a computing course that was equal to an Int2. Now I do an HNC (first year degree sort off) in computing.