I had studied in the UK, and GCSE is普通中學文憑考試,主要比Year 10-11 students to study about 8-10 subjects include 5 core subjects are English Maths Phyics Bio and Chem, and IGCSE is same as GCSE but it is more suitable for intanational students and most of HK intanational schools will use it coz it will easier to 函接IBYP, but most of the UK schools will use GCE during Year 12 and 13, then they need to choose 3-4 subjects which they prefer to study.
Also my children are 3 and 2 years old and we live in the UK as well, coz here is better than HK.
If u have any question about the UK education then u can ask me here.
WKF have communication session on last Friday evening regarding DSE and IGCSE proposals. Not sure how many students will study IGCSE after this communication session.