Maths is an interesting one as its one of those subjects where an A* is significantly more challenging compared to some other subjects (less than 20% get A or A* at A level if they got an A or A* at GCSE?)
Plus, DfE data shows that most predicted grades are at or above what student actually gets (but a small percentage do get better than predicted)
How strong is your Personal Statement?
If it was me I might go for a couple of Unis who say A* Maths requirement (you have A* Econ predicted) for the hell of it, and have some strong insurance choices because there is risk when applying to oversubscribed courses
Alt - do any of the "Economics with / and" courses appeal to you? They can be less over subscribed and more flexible on grades. My daughter was looking at Economics at St Andrews, Economics with Mandarin was significantly less subscribed and they were willing to make a really generous offer