hiya
well done on getting your interview! wear something smart, what you said sounds good
I dont think your hair is the most important thing, just as long as it is smart. Does it look smarter up or down? If it's really long, up might be better, but i wouldn't stress too much about it.
think about answers to obvious questions that they will ask -
why do you want to be a receptionist?
can you tell us about when you helped somebody?
can you tell us about when you used your initiative?
where do you see yourself in five years time?
what do you like to do in your spare time?
what would you do if.... somebody complained / was rude to you / etc
these are just examples, and knowing my luck they'll ask something completely different, but it's worth thinking about these sort of things before you go in
good luck xxx