I am currently doing Economics in Year 13. Many friends at my school start Economics at A-Level so it is certainly fine. In fact, many schools only start offering it at A-Level so I don't think there will be a huge issue. Economics A-Level is not a requirement for most Econ courses, so make sure to check. Having it as an A-Level may help, but if you think you are going to struggle, I think taking something else might be a better idea. Economics A-Level is a lot of (almost all) essay writing and not much Math. It is about understanding fundamental concepts, how you structure your answers and make arguments + evaluate them. However, it is a very time-pressured exam, compared to my other A-Levels (Chemistry/Biology/Math).