Lots, but depending on your political views - you can pigeon hole your class (as per Bown's ideas of the British Public), therefore drinks:
Labour (good working stock) - Beers, must be British, none of this poncey European blonde fizz. Accompany with crisps, peanuts and crispy cereal snacks (preferably Supermarket own brand, if you go for branded crisps, etc. you are more likely 'New Labour' or a wannabe Lib Dem).
If they win, celebrate with a bottle of Tennents lager - looks like shampoo and taste great for a labour supporter.
Liberal Democrats (socially conscious middle classes) - Contiental Beers and/or wines at no more than GBP6.00 a bottle (preferably new world).
Accompany with Kettle Chips, cashews, almonds, hazelnuts, bombay mix, etc.
If they win, celebrate with a bottle of Cava or Prosecco.
Conservatives (traditionally upper middle classes/upper classes (Toffs)) - No beer, unless it is a very select limited production specialist beer, such as Belgian Trapiste Monk's beer, brewed for a special occasion. Mainly drink wine from a respected maison/casa, belonging to a well established European family; only European wine because the New World Oiks need to be put in their places. Bottle price not less than GBP12.00 a bottle.
Accompany with a well thought out finger buffet, including but not limited to, Smoked Salmon, Smoked Halibut, Raw Tuna (flown in from the Japanese markets today), Beluga Caviar, a few poached Dublin Bay Prawns, a selection of continental hams and cured meats (Ardennes, Serano, Parma, Milano, etc.), Foie Gras d’Oi, a select choice of continental salads, 6 continental cheeses (produced on small, select farms), hand made savoury biscuits, a selection of various continental breads made into rolls and a selection of 6 sweet finger pastries made from the finest and freshest creams and fruits.
Of course rather than do this yourself you should contact a local catering company to do this and provide service staff until you wish to dismiss them; or you could telephone Harrods or Fortnum & Masons and get them to courier your light repast for this evening.
If they win only a bottle of Krug will suffice.
Green Party (environmentally friendly middle class) – Anything that is not damaging to the environment, however I would expect some home made bramble or gooseberry wine and home made ale/bitter made from hops grown on the local farm; perhaps your own scrumpy or perry.
Accompany with crudités (cut raw vegetables) and an environmentally friendly dip, whole grain bread, home made cottage cheese, home made biscuits, cakes and the first fruits of the season.
If they win, you will not have planned for this, so open another bottle of Gooseberry wine, or the home made brandy, made from your fruit wine of 10 years ago.
Other parties follow similar logic……