Economics without Maths

Not much. I have a friend who did English instead of maths and was accepted at Oxford for a PPE degree. (She also applied to other unis for Economics and was accepted by them).
You can most likely get away with not doing maths, as long as you got a decent grade for it in GCSE.

How much does not having maths limit the opportunities to do Economics at University or to get an Economics degree.

I'm a final year econ student who didn't do A-level maths. Honestly, it is limiting factor if you're a high-flying student looking to go to a top 10 uni; I mean I can believe AnxiousNobody's friend got accepted for PPE at Oxford without maths but no way will a uni of that calibre accept a pure econ student without maths. You still have plenty of options outside the elite unis though, I made it to a decent RG uni.

My course required an A at GCSE and some of the maths we do is degree-level maths, so it's pretty demanding if you don't have an A-level. I do a BSc however, which generally has more maths than a BA (though not always). If you're not confident you can make the step up with maths I'd look more at BA courses.