Good luck Dee - take it one day at a time and it will fly by. I've posted this somewhere before but dont think of it as "no food/alcohol for 3 months" but instead think "I will stick to SS 100% today" and you'll be fine.
Set yourself little goals and rewards for each one -write them down before you start so you can look forward to them.
Write a list of all the positive things about losing weight that you are looking forward to (wearing floaty dresses, fitting into airline seats, running half marathons - whatever).
Experiment with the shakes and soups, try them hot/cold/blended with ice/ thick/runny etc and you'll find out which you like. I thought they were rank on the first day but now I find them quite tasty.
Tell your close friends and family that you are doing it so that they dont arrange lots of dinners/drinks which you can't go to - you'll find that they will probably be really happy to go for a walk/have nails done/ go bowling or cinema instead of eating and drinking.
Personally I am really strict and don't deviate at all from SS unless its totally unavoidable (ie a client lunch at work). I know that the minute I let myself eat something that's off SS, even if its just a morsel of cheese or a bit of chicken then I will be a step closer to giving up altogether. You probably have much stronger willpower than me but at the start (I'm on day 7) I need to be really strict with myself.
Good luck! As soon as the weight starts to come off you'll be sailing...