nicker = a pound (£1)
pony = twenty-five pounds (£25)
quid = one pound (£1) or a number of pounds sterling. Plural uses singular form, eg., 'Fifteen quid is all I want for it..', or 'I won five hundred quid on the horses yesterday..'.('quid' first appeared in late 1600's UK.)
readies = money, usually banknotes. Simply derived from the expression 'ready cash'.

squid = a pound (£1) 'It cost me Fifty squid'.
score = twenty pounds (£20).
sov's = pounds. Short for sovereigns - very old gold and the original one pound coins. For example 'Lend us twenty sov's..'
tenner - ten pounds (£10).
ton = commonly one hundred pounds (£100)
wad = money. Usually meaning a large amount of spending money held by a person when out enjoying themselves.
wedge = a pay-packet amount of money.
wonga = money