There are many English and Irish pubs around the centre of Prague if you miss home they always have a good party atmosphere in them and usually big screens up with English sport showing on them so you can catch up on the latest football scores. Most of them serve food as well. If you are after a good pint of Guinness the obvious place to head for is one of the Irish Pubs, like
The Shamrock Irish Pub which also has live music, or
Rocky O'Reillys. If you fancy some egg and chips with your pint there is always somewhere like
The Lion British Pub just off Wenceslas Square. There are also plenty of Sports Bars around the centre with big screens to see all the latest sports while you are having a drink as well as things like pool tables.