It's not a problem. I did Further Maths, but Uni maths is completely different anyway. My friends who did not do Further Maths had no problem. It may help with a couple of courses on integration and differential equations in the first year, but everything else is completely different, and Further Maths is nothing to do with the majority of uni maths, especially the pure stuff, even in the first year. And even then, where any overlap with A-level happens they teach you everything all over again. From my first year, I would say further maths would have helped a fair bit with Math 3 (these are just random course names), and a bit with Math 5, and maybe math 6 (we did 10). Math3 was integration, differential equations and A-level revision. Math 5 was matrix algebra and then double integration.
Everything is new, or where it is A-level material, it is viewed from a completely different point of view. Maybe 20-30% of first year material is familiar from A-levels, and after the first year it is basically 0%, it's all new.
Our Prof Dimitri always used to say that in teaching analysis, it may even have been better not to have seen an introduction before uni level, and to not have met the subject of analysis without the proper treatment of limits and convergence you get at degree level. He stressed the need for appropriate definitions, which may be airbrushed at A-level.