Quant related questions...

Hello everybody, y13 student here.
I'm a passionate student who wants to study Maths and get at least a masters in it.
i will be going to imperial (i hope) for studying Maths and want to go to an even more prestigious Uni for my masters/P.h.d or at least that's my plan rn.
 

I'm great at Maths, maybe not a genius but i am great and that's important.

I have never competed in any Olympaid/Competition for maths except for last week in th UKMT challange and the reason is that i just moved to the uk a few years ago and had many more things to worry about, as well as my english which is still not on an olympiad level, but i felt comfortable with the challange i took part in last week.
You might ask why i didn't participate in any competition in my home country, Well unfortunately it's rare to be lucky enough to be recognised and be trained for olympiads and etc.

so my question is if it's a necessary and sufficient to do olympiads and these sort of things to break into quant?

if yes, how can i guarantee myself a ticket to this career without having participated in these competitions?

You might say if i were good at maths i'd be going to say oxford/Cambridge to study maths, but trust me immigration has many down sights, and in my case i wasn't able to do as good in my GCSE's
 

I tried to keep it short and detailed, so please forgive me if it sounds egoistical.
I wanted to thanks in advance to whoever who comments.