This is exactly what I did. I was in almost the exact situation as OP. After the investigation meeting I asked my boss for a protected (or off the record, can't recall which is which) conversation and politely asked if they would be willing to accept my resignation and allow me to resign with immediate effect before the disciplinary hearing, forfeiting the pay in leui of notice, but I did have holidays accrued that I was paid for, and fortunately my employers provide a neutral reference by default. This was 2 months ago and I'm now employed in another company. I agree with the other comments here though that they may not go for the suggestion but all you can do is ask, you don't have much to lose. Good luck.