A reference to the Selby rail accident might be relevant here. That occurred when Gary Hart fell asleep at the wheel, causing his vehicle to end up on the train tracks. He was found guilty of causing death by dangerous driving. That was because the Crown Prosecution Service (and subsequently the jury) took the view that, irrespective of the standard of his driving up until the point where he fell asleep, he was driving dangerously because he should have been aware that he'd had insufficient sleep before driving.
So there's possibility (and no more) that the police and CPS could consider a prosecution for 'dangerous driving'. If they succeeded in obtaining a conviction, you'd automatically be banned from driving for a minimum period of one year, plus you'd have to re-take your driving test to get your licence back.
However Gary Hart was only convicted for dangerous driving because it could be shown that he should reasonably have known that he was over-tired. (For a charge of 'dangerous driving' to be upheld, the actual legal test is that the prosecution must show that the standard of driving fell well below that of a reasonable and prudent driver). You should be extremely careful about what you say to the police, avoiding anything which might suggest that you knew you were tired. Then the only realistic charge will be one of 'driving without due care and attention'. That could still possibly result in a ban but (with a guilty plea), 6 to 9 points on your licence is the more likely outcome.
Chris