Hi mate, yeah I tried this. I played for about an hour after putting in £20 and getting an extra £20 from the betting company (William Hill I think it was). I only played with £1 bets, never changing it.
I have to say it worked for a while but the more you play on, the more you risk getting that row of wrong spins that wipes you out. Also, the fact that I was betting only £1 at a time, meant I was only making £1 on each bet. So even if you end up doubling every loss to the point you've put £32 on a roll and then win, you'll only make £1 on the original total before your first loss, if that makes sense?
Also, if you're putting £1 bets on with a £40 bank the number of continous wrong rolls before you're wiped out is only 6. I found I sometimes came to within 4 or 5 and then luckily rolled a correct one but, like I said, I played for about an hour and made around £15 on top of my total and should really have stopped there but I played that one roll too many haha and lost it all!!
If you were going to do it I would suggest playing maybe 50p - £1 at a time and then quitting once you made £5. Don't get tempted to just keep spinning and spinning because you never know when the odds will tumble against you.
I don't think I'd ever try it again but I'm glad I did. Good luck with it buddy! Let me know how it goes
P.S. If you can find Derren Brown's video of how he got 10 heads in a row from tossing a coin it will explain a bit on how the odds of continuous spins from a 50/50 chance works. Best of luck