I'm so sorry this is happening to you @Questionairballoon and I think you are getting a ridiculously hard time on here!!!
I don't know much about 'the rules' these days, (my DC are in their early 30s now) but I can only advise you to hold your hands up, admit you're at fault, and say you're really sorry and it will never happen again. It's not like you have kept your children off for half the bloody academic year is it?! Yeah, keeping your children off school for 3 weeks off in a row for a holiday, (with no permission from the school to do so) is not great, but it doesn't deserve for you (and your DH) to have a criminal record - IMHO. It's ridiculous IMO to land you with a criminal record for this!
Me and DH kept our 2 DC off for a full month - the last week of June, and the first 3 weeks of July when they were 7 and 8, (around 24-25 years ago,) to take them on a trip to Canada, and America, to see family members who they had not seen for 5-6 years (and didn't remember, although the family members remembered them.) We also spent a week in Cuba.
However, we asked the school if this would be OK, and sent in a written request, and the school wrote back and said 'yes, just this once,' as it would be a really exciting and educational and cultural experience for them. We weren't sitting on a beach in Corfu for a month, we visited 3 different countries, and our DC experienced all sorts of sights and cultures and people.
This was nearly 25 years ago though, and it may not be allowed now. I know just 5-6 years later, the schools got much more strict, so I'm glad we did it when we did. They weren't given any academic work to do either. (Last week in June, and first 3 weeks of July the academic year was winding down, and not a lot was being done, so they didn't really miss much, and they've always been quite forward/advanced academcially, so the month off made no difference to anything.)
I hope it's all OK, and that you don't get a criminal record. I think you should see a solicitor and ask if the 'charge' can be reduced, if you admit you're wrong and it will never happen again, and hopefully it will just be a fine.
Good luck!