stay in a close time zone and have an excellent telephone and Internet connection that you don't mind using extensively. You never know.
I agree with this if you are in a situation where you are fairly confident that your child is going to get what they need, But if you think that your child is borderline case in terms of getting the desired/required results and will need guidance from the school, I would strongly recommend being around.
I work in a school. On results day we have 260 young people getting results and all careers staff are on standby to help the ones who didn't get what they need. Priority assistance will ALWAYS be given to those pupils who are here in person, and that means that anyone phoning or emailing will have their contact details taken and will have to wait for a call-back. And this can cause distress, frustration and occasional crossed wires: if you are not around, accept in advance that you are not going to be a priority.
We always advise that pupils and their parents be in the country on results day. If you can't be, make sure that all permissions for a third party to collect grades/represent your child in his/her absence are arranged in writing with the school before the teachers all bugger off on their holidays....or they will refuse to hand out/discuss problems on the day.
In my mind, being around in person to deal with any fall-out on A-level results day, and making any required decisions about the future, is part of being a grown up: I mean that mainly in relation to the students but I guess probably applies to the parents as well.
Hope it goes well for you OP!