Customs: The UK, especially
London, has many local customs
Now you are in England, there’s no excuse (especially in the autumn) not to play ‘conkers’. Two people stand opposite each other holding strings to which is attached a horse chestnut (a conker) soaked in vinegar to make it hard. Each person then takes turns to hit the other’s conker and destroy it. Keep you fingers out of the way. Good clean fun, and the English are current world champions at it.
If you can, look out too for some of our stranger local customs. 
At many village greens in England during the summer (once the cricket’s finished) there is Morris dancing, when two sets of grown men, with feathers, blacked-up faces and a set of sticks, dance jigs for charity money and a free pint.
In some Cornish towns there are parades with giants and ‘obby’orses made out of paper mache and odd scraps of material and the men put on dresses as lords of misrule, a peculiar habit you can still witness in theatrical pantomimes (put on mainly for children) which occur at Christmas and are best known to Americans in the antics of Monty Python’s ‘Spamalot’. Some actors cross the Atlantic to star in them: in 2006, it was Henry Winkler's turn as ‘Hook’ in ‘Peter Pan’.
Then there is Guy Fawkes night on November 5th when we remember the attempt to blow up Parliament and burn a ‘guy’ on a bonfire and let off fireworks. Guy Fawkes day is now joined with newer ethnic celebrations such as the Hindu Diwali (October 21st) and Moslem Eid (October 24th) where more fireworks are let off.
On August ‘bank’ holiday, there is the biggest carnival in Europe in Notting Hill, brought to our shores by the population of Trinidad who began arriving in the 1940's and by the early 1960's felt sufficiently homesick to initiate a carnival when they finally realised that Britain had no sun!
Then there’s the Lord Mayor’s parade (London actually has two mayors), the annual Boat Race (between Oxford and Cambridge), the Henley Regatta, oh yes and even the Changing of the Guard. Join in and become an English eccentric.