HM Revenue & Customs guidelines suggest the following quantities;
Alcohol; Wine OR Champagne - 90 litres (120 bottles), Spirits - 10 litres, Fortified wines - 20 litres, Beer - 110 litres (just over 10 cases).
Tobacco; Cigarettes - 3,200, Cigarillos - 400, Cigars - 200, Smoking tobacco - 3 kg

I don't think for one minute a 16 yr old would be allowed to bring any of the above in.