Yes, at my school you have to inform them beforehand if you want them posted: they won't email results (though they might at other schools) and i don't think any schools give results over the phone. Definitely ring up beforehand if you want to try to get them posted/emailed.
If you're not away yet, you could write a note to a friend/someone who is going to results day and sign it - at our school they are then authorised to pick up your results for you (you would have to do the same if your parents were picking them up).