How good at music do you have to be?

Your Question
How good at music do you need to be?
Hello, I was just wondering how good at music do you need to be to go
to a music conservatory or study music at university? And I'm thinking
about really good universities.

I'm really interested in music but I could do basically anything else
I wanted to do, so I want to know whether I should just pursue
something else.

A bit of background info:
I play the piano and the violin. The piano for 6 years, violin for 8
but I moved to a country where they didn't have good music facilities
so I stopped playing both for two years. 3 years ago I moved again and
restarted piano but they didn't have a violin teacher in my new
country so... I'm also v. interested in composition.

I passed grade 5 theory and I recently passed grade 6 piano. The last
grade violin I did was 3 and that was ages ago.

I'm just worried because I haven't exactly had a good music education
since I left the UK and I don't think I know enough or am good enough.

Thanks a lot.