Hi, I take Geography, Economics, Maths and Further Maths A levels
I think it is a very good combo as it leaves your options relatively open - you could go on to do any of those subjects at a good uni, although I think that combination lends especially well to an Economics degree.
As for Further Maths, it definitely isn’t impossible by any means - you just need to make sure you are consolidating, and ask the teacher any questions you have instead of just forgetting about the stuff you don’t understand.
But remember, four A levels is a very intense workload, which will be even harder with the Welsh Bacc (tbh idk how much of your time that will take up i dont know anything about it)
I hope this helps!