A Levels on separate years for cambridge

Hi all. I am in year 13 right now, and am planning on taking a gap year next year, then applying to Cambridge then. Because I feel i wont get in if i apply this time. Would Cambridge be alright with me taking 3 a levels this year, getting real grades for them, and then applying with a predicted grade for a 4th subject (further maths) which i would then complete in a gap year? Would doing three the first year and one the second year in any way disadvantage my application as I heard Cambridge want all a levels to be done in the same year. Please help

You'd likely be given no offer or an unconditional based on your 3 achieved grades anyway. If you are applying for a course that prefers Further Maths, they might ask why it wasn't done at school.
Why do you feel you won't get in this year?

I got A*A* B B for predicted grades where most people from my school get in with 4A* (it’s an independent school). The minimum offer is A*A*A so there would be no chance of getting in this year, so I will take a gap year and apply again. I will either drop further maths, and get 3A* and apply with that , or keep further maths and risk not getting 4A*. Would my Cambridge application be disadvantaged if , during my gap year I applied with 3A* real grades and 1A* predicted for further maths?