Am I more likely to get accepted at a good uni if i do their foundation year?

By "good uni" i usually mean Oxbridge & Russel Group universities by the way.

I don't mind taking a foundation year btw. To be honest, I don't think I'm unqualified for those universities, but entry requirements for my country are EXTREMELY high and I wouldn't want to gamble with my future by applying to good unis.

Oh and just so you know, students in my country can't retake their exams if they're unhappy with the results (they can only retake them if they've failed).