That's easy. The number of possible combinations is 13,983,816 as already shown.

The number of desired combinations is C(6,n) where n is the number of correct balls.

So to win the jackpot, C(6,6) which is 1 so 1 in 13,983,816 chance.

To win on 5 correct numbers, C(6,5) which is 6 so 6 in 13,983,816  chance.

C(6,4) = 15

C(6,3) = 20  (a 1 in 699,190.8 chance of winning a tenner)

Edited to say: this is of course nonsense   See below!