All non-alcoholic drinks are free for the duration of the flight as long as they don't run out. I drink coke zero and that tends to be popular at times.

The rule of thumb seems to be that every time the drink cart passes you you can ask for one free alcoholic beverage. They usually do a pre-meal drinks service and also bring the cart around with the meal. You could ask wine both times to get two small bottles, which is a good bit of wine for an airline meal.

Failing that you should be able to purchase some more by pressing the call button or possibly through your IFE. Won't break the bank and not something to worry about

Unless of course this is a British "glass or two", in which case it may break the bank .