Buying a round of drinks at a pub is the most common way of celebrating someone’s birthday.
Unlike many European cultures, the British enjoy entertaining in people their homes. If invited to someone's home, it is normal to bring a host/hostess gift of a box of good chocolates, a good bottle of wine or flowers.
Champagne is always appreciated. Liquor or spirits, on the other hand, are a matter of personal taste and are best not given as a present.
Do not bring red roses, white lilies or chrysanthemums.
Whenever you have been a guest in a home, you should definitely send a hand-written thank you note.
If you are giving electronics, make sure that its electrical plug is their standard plug. Also, DVDs from other countries can be of different formats to those in the UK. When giving a DVD, you should make sure it is of the correct format.