What after university what job?

I live in england and im in year 11 going into six form in september

After six form I am looking to go to a good university I am going to apply for oxford and maybe the london school of economics and social science.

But I have been asked to name my dream job

I have no idea…

I’ve always wanted to work on something like nasa but I dont really want to leave the country

Whats making this so hard is that I dont know what I am going to do at university yet…

It will be something to do with maths Maybe physics , economics or computer science

Any ideas for an exciting job that I could do with any of those qualifications?