For Americans, AYBS? is quite an introduction to British colloquialisms.  Here's an introductory glossary.

above oneself presumptuous 
Alsatian German Shepherd
agro aggravation
apple crumble apple cobbler, apple crisp
argy-bargy squabble
banger sausage, jalopy
Bath Oliver Biscuit similar to a graham cracker
berk dope
biro ballpoint pen
black spot danger area
bog loo
bonnet car hood
booked made a reservation
boot car trunk
braces suspenders
bubble and squeak greens and potatoes with meat fried together
bullocks balls
busker street entertainer
cack-handed clumsy
castor sugar icing sugar/ confectioner's
catapult slingshot
cave/cavey keep cavey- stand lookout
char abbr. charwoman- cleaning lady
chipolata small pork sausage
clever dick wise guy
clippie female bus conductor
cloth ears deaf
cock up create a mess
combinations, combs long underwear
commissionaire uniformed doorman
conker horse chestnut
conkers a game played by tying string to a horse chestnut and knocking against another players' conker
council flat public housing
diddle screw
dog's body gopher
dole, the unemployment
each way bet win or place
electric fire heater
elevenses coffee break
E.N.S.A. Entertainments National Service Association
fag cigarette
faggot spiced meatball; small wood bundles
fairy cake cupcake
fell off the back... lorry hot
fiddle cheat
flat apartment
flutter small bet
fortnight 14 days
fruit machine one-armed bandit, slot machine
get knotted stop bugging me
get one's cards pick up pink slip/ walking papers
get stuffed get lost, also get f*%$#
get the chop get fired
get the wind up frightened, jumpy
get your knickers...twist get excited over nothing
get up one's nose get in someone's hair
gin and It gin and Italian vermouth
Girl Guide Girl Scout
git jerk
give over come on
go missing disappear
go to the foot of our stairs I'll be darned
go off tire of
Grace and Favor describes a residence occupied rent free courtesy of the monarchy
grotty cruddy
ground floor first floor
guide dog seeing eye dog
guinea a coin worth 1, 1shilling
gym slip gym suit
haberdashery notions
hair grip bobby pin
hard cheese tough luck
have had one's chips you've had it
have it off have sexual relations
high tea tea including eggs, bangers- light supper
hockey field hockey
holiday vacation
home and dry achieve one's goal
hooter nose
hoover vacuum
hunter pocket watch with hinged covers
jankers military jail
jerry German (derog)
jersey pullover
jim-jams pajamas
jolly very nice
jug ears ears like pitcher handles
jumper see jersey
kip sleep
kiss of life mouth to mouth resuscitation
knacker's yard animal rendering plant
labour exchange employment office
lacquer hair spray
lie in sleep late
lift elevator
lino linoleum
liverish glum
loaf head
local neighborhood pub
locurn doctor on call
lolly money
loo bathroom
lorry truck
lost property office lost and found
lumbered with  saddled with, put upon
moggy  pussycat
monkey nut peanut
NAAFI Navy, Army, + Air Force Institutes
nail varnish nail polish
nanny child's nurse
nappy diaper
newsreader newscaster
nick arrest someone;  in the nick- under arrest
nicker quid, pound
nippy waitress
nip round visit,  pop round
nob head
Norfolk turkey native of Norfolk
not on impracticable
not on your Nelly rhyming slang- not on your life
nought also naught zero
Number 10 Prime Minister's address
nutter crazy person
off license liquor store
off the peg off the rack
on appro on approval
one off one of a kind
on form in great shape
on the game to be a prostitute
Our Ada our refers to a relative belonging to "Us"
packet package
paddle to wade
palaver affair
panda car police car
panto, pantomime Christmas theatre-traditionally fairy tales with  varieties of entertainment
pants underwear
paper knife letter opener
Parson's nose chicken bum
pasty sim. to a knish
pavement sidewalk
peckish empty
penny dropped he got the message
petrol gasoline
pink gin gin with angostura bitters
pinny apron
pip beep
pip at the post nosed out
plum duff plum pudding
po chamber pot
pong stink
poof pansy, cushion
posh stylish, smart
Postman's knock game like post office
Pub crawl make the rounds at pubs
pudding, pud dessert
Pudding Club pregnant
pull one's socks up shape up
punch up fist fight
puncture flat
put one's back up to upset
put one's feet up relax
put the boot in kick hard
query. complaint
queue get in line
rag and bone man junkman, peddler
raver knockout
redundant unemployed
removal man moving man
rising damp moisture in the walls of a house
roll up come over here
roundabout merry go  round
sauce, sauce box cheeky
savories tidbits (cheese, pt, hors d'oerves)
scrum melee
scrumpy rough, hard cider
season ticket commuter's pass
sellotape scotch tape
semi-detached two family house
sent to Coventry to turn one's back on
shandy beer and lemonade
shepherd's pie meat hash topped with potatoes and baked
short back and sides crew cut
skint dead broke
skirting board base board
snip bargain
spend a penny use the washroom
spotted dick sponge cake with currants or raisins, steamed, served with custard sauce
starkers stark naked
stop to stay
sultana white raisin
sweets candies, preserves or dessert
swizz swindle
tart up to doll up
tiddler minnow, shiner
tights pantyhose
toad in the hole sausage baked in batter
toff a swell
toffee-nosed stuck up
Trades Union labor union
transport cafe all night truck stop
trillby slouch hat
trolley a pushcart
twig catch on
up the spout in a fix
V.A.T. value added tax; sales tax
vest undershirt
way out exit
week a week from...
wellies Wellington rubber boots
whip round collection, pass the hat
Wimpy Wimpy Cheeseburgers are similar to White Castles
wind up raise one's hopes falsely
winkles small edible shellfish
zed Z