Largely depends on what you're actually drinking, I'm not a heavy drinker myself, usually only have 2 or 3 beers, which is around 30grams of carbs, I think DAFNE advises that you should usually take half the amount you would usually take for carbs if you're taking them in with alcohol (in my case i take a half a unit of insulin per pint). If you're drinking alcopops or stuff with full sugar coke etc then that'll be a seriously difficult night to manage and wouldn't even begin to guess where you should start! You'll need to find out how many carbs are in your drinks before you can begin to work out how to manage the insulin needs.
Alcohol makes your sugar level rocket up and then it drops gradually over a long period of time, i've heard of people having hypo's the afternoon after they've been out the night before due to alcohol, good advice about the pizza, would be a good idea to have something like that before you go to bed, pizza is really high in fat content so takes a loooong time to absorb the carbs, it would even out but not completely nullify the glucose drop from the booze.