Unless the owner of the villa, the villa's cleaners and the family who are due to arrive next after you were the organiser, band and hosts of the concert, then YWBU to overstay, as they are the ones who you would be passing your convenience on to.
It wasn't your fault that the concert kept you awake, just as it wouldn't be the fault of the owners, cleaners or new guests if their day were to be disrupted by you staying on past your agreed check out time.
I totally understand where you're coming from though @Nextphonewontbeasamsung - I'd be pretty pissed off at being kept awake when I had a long drive (particularly one where I would have to drive on the 'wrong' side of the road 
) ahead of me the next morning. It would feel good to hold someone accountable and I think in this case, I'd find it cathartic (once I was safely home – or I’d dictate it to DH to help me stay awake as I drove!) to find the email address of the concert organiser and let them know how disappointed I was with their lack of consideration towards people who had travelled to visit their area, only to be aurally assaulted until 2:30am, without any prior warning. I'd also leave shitty reviews all over the internet for anything or anyone connected to it - but then I can be really petty!
I would also make sure that you detailed your displeasure at the failure to inform you that the concert was happening when you next contact or review the villa/the owner/your overall experience. Make sure that if this is a regular event, they realise that it's imperative that they let their guests know in advance. Had you known about it yesterday morning for example, you would have had time to get in touch with the owner and organise a later checkout time.
Is it worth trying to get in touch with the owner when you wake up tomorrow and organise it at the last minute? Or if you have their email address, you could just drop them a quick email (now, if you're still awake) saying something along the lines of:
Hi Owner,
As you may be aware; last night there was a HUGE concert right outside our villa, which we had not been informed about. The ridiculously loud music continued until 2:30am, so none of us were able to sleep much before 3am. As you know, I am due to drive back to the UK today and will now be facing this long and challenging journey on just 4 hours' sleep, which I'm sure you'll agree just isn't safe. If we had been told about the concert in advance, we could have worked around it and perhaps had a siesta yesterday afternoon to ensure that I'd had enough sleep. As it stands, I would not feel safe to drive on so little sleep, so need to be able to catch up on the sleep I have missed, which I estimate means that we will be ready to leave the villa at midday, rather than the previously agreed 10am. I'm sure you'll agree that safety comes first, and I'd hate for there to be an accident simply because I wasn't able to sleep for the extra couple of hours I needed. I understand that you may be a little concerned about the cleaners getting behind schedule due to our new midday check out time, but please let me reassure you that we are perfectly happy for the cleaners to begin their work from 10am, and would only ask that they don't enter the bedrooms until we are all up and about, so that my sleep is not further disturbed! I must try and get to sleep now, but I will see you at midday tomorrow, where we had previously arranged, so that we can hand over keys etc.
Many thanks for your understanding in this matter,
@Nextphonewontbeasamsung Family
Good luck OP, I expect you're fast asleep now and that the owner is understanding and takes pity on you in the morning. I hope you have a safe and uneventful journey home!