”Foreign Food” being limited to the occasional Italian, Chinese and Indian restaurant (all serving dishes heavily modified from the originals to suit the British palate.
The dishes served in most India restaurants (usually staffed by Bangladeshis) still bear no resemblance to those served in Indian homes, usually they are too sweet and too salty
Chocolate Cigarettes (gone)
I remember candy cigarettes, the only chocolate ones were one my Dad brought back from Germany.
Sweets from large glass jars, weighed out into paper bags
There are several sweet shops locally (East London) that sell loose sweets in paper bags.
”Proper” butchers with carcasses hanging in the window (pretty much disappeared today, I think)
Likewise, there are several traditional butchers in my area.
Double-Rovers (combined LT underground and bus pass)
They are called 'One Day Travel Cards' and work on all TfL services.
Wooden escalators
The Kings Cross fire meant the removal of wooden escalators, probably for the best?
Ham, cut off the bone as you waited (and whatever has happened to “York Ham”: boiled, de-rinded, rolled in yellow breadcrumbs and then sliced to order?)
Ham 'off the bone' is available in most supermarkets, on the deli counter, plus specialist delicatessen shops.
Cadbury’s Smash (instant mashed potato)
You can still that in my local Tesco, Asda, Sainsburys.
BabyCham (pseudo Champagne - marketed as being a “sophisticated” drink)
It's called "Prosecco" these days.
Black and White TV
They still issue B&W TV licences, 7,000 in the latest figures.
Milky Bars
You can still get Milky Bars in various sizes.
Skool Uniform of short trousers and blazer, plus cap (not forgetting white shirt, skool tie, knee-high socks and lace-up black leather shoes)
Many junior and infants schools have uniforms with shorts, plus the rest.
Leather satchels for skool.
School style satchels are very fashionable, and expensive, albeit not for school children
Proper plimsolls!
Converse make "plimsolls", canvas lace-up or elasticated shoes.
The wooden ruler and/or cane as punishment at skool
Beating children was never really a good thing
Walnut Whips (I haven’t seen those for ages..)
Still made in various sizes.
Dare I suggest you haven't been looking?