[Daithi]

Since you said European casino I'm going to assume we are using the French rules where there is only a single 0 on the wheel, and if you placed an even money bet and the ball lands in 0 then the "en prison" rule applies and the even money bets continue to ride.

So, if you bet everything in 1 shot your odds of winning are 50/50. However, you can improve these odds.

Let's assume that £1 is the minimum bet. Then you can make a bet of £3 to get to your £160+ goal. If you lose this bet then you'll need to increase your wager to cover your previous loss as well. You can actually make 8 losing bets before you won't have enough to cover all your losses with a single bet. The chances of losing all 8 bets is 1 in 256 (1/2^8), so you will win 99.6% (255/256) of the time. However, even if you lose all 8 bets you will still have a little money left over, so your odds of winning are actually a little better than even this.

If £5 is the minimum bet then you can only make 5 losing bets before you are broke. This is 1 in 32 (1/2^5), so you will win 96.875% (31/32) of the time.