Okay, I decided I wanted to do computer science at churchill college, cambridge when I was fourteen so I know how you feel about having a goal at a young(ish) age. I'm also asian. I had already started GCSEs by the time I decided I wanted to study computers, non of my optional choices have anything to do with computers, ICT looked like s*** so I suggest you don't take it and do something that you may enjoy, I personally took triple science, DT, Art, German etc, I think DT helps develop identifying client needs and meeting them, researching relevant stuff etc. GCSE is easy and not too relevant when applying to universities, but straight A* and A do look good, no matter what subjects you do, I know at the moment GCSEs will look daunting and huge but believe me, it's reeeeaaaly not. In A levels, I'm taking maths, further maths, physics and computing, I only really started getting into programming at 16 so if your school/college does to computing a-level (AQA) I'd take it, it'll help with your personal statement(personal projects, subjects of interest etc) and show that you have legitimate interest and know what it is that you're going to take up. Do lots of reading, computer science books, although at the moment maybe not the undergraduate level books that universities suggest as preliminary reading. Extra curricular stuff help as well, it's known that children exposed to classical music are generally smarter, I've done grade 8 piano and flute, both distinction, don't know if it really made me any smarter but It helps boost up your ucas points (150 for my two) and show that you have a diverse range of interest. Sports and keeping fit will also help you show diversity but also help your life at school, personally, I don't have much problems with being picked on, I took care of any bullies or the like when I started secondary school, being physically fit, I think also help you focus on studies. I don't think there's much need to worry too much about the computing olympiad although it does look amazing, it's not necessary to be successful in computers, I personally did maths olympian papers and stuff but haven't really got much out of it.
So just keep up the optimism, try your best in school, make the right choices, keep diverse, be prepared, and I' sure you'll succeed in any route that you decide to take.