[mellett68]

Vacation / Sick time is a bit different than needing to run errands till 10am, either shifting the working day round a bit or spreading the time out over the next days or week etc.

Doesn't hurt to check in when you're available again as a courtesy but the benefit is NOT having to get permission to do something like this up front.

If you're remote as an employee then presumably the company has process around holidays and stuff that would be followed. If you're a freelancer then part of what stops you, and your client, from being fined by HMRC (in Britain) is setting your own working hours and days.