i moved out a year ago at 18 and i was so clueless! here's a couple tips to avoid some of the mistakes i made
have a debit card, but no credit cards. if you must have one, put £10 on it and leave it in a drawer. it'll help your credit rating immensely, and that's something you really want. you don't want to get into credit card debt at such a young age.
make a weekly AND monthly budget, and stick to it as much as you can. include a "treats" section, for unplanned occasional nights out, or that new top you really really want. be real about it, and if it doesn't work, change it.
try to set up a separate account for savings that doesn't have a card. make a standing order to it from your regular account of even £15 a month and it'll slowly climb to a large amount if you leave it alone.
learn to cook simple dishes like tomato sauce for pasta, or bean burgers (email me for recipes, i've got loads now. most of them have you eating in 30 mins or less =] )
learn to use a washing machine. it may sound simple, but when i moved out i didn't have a clue really.
make sure you know what do to in an emergency. have the number of your local police station, the gas, electricity, phone, water companies and a neighbour right by your phone. stick a sheet of paper next to the phone with blue tack.
are you moving in with flat mates or on your own? right now i've got awful flatmates, really horrible pieces of work, and you need to learn how to deal with people who try to make your life difficult.
learn how to shop. this sounds simple, but it isn't always. take your mum or dad with you to shop for your family this week, and get advice from them on what's best for your budget.
get used to washing dishes. i recommend wearing washing-up gloves personally.
don't do what i did and leave a plastic bag next to a hob while you're cooking. i almost burnt the kitchen down.
have several keys cut to your place. know where they are. they're so easy to lose!
install locks on windows and doors and make sure they work!
call home once a week at least, especially if you're home sick!
email me if you need anything more, i know how tough it can be living without your parents for the first time.