To pick up from DevSolar's comment:
Generally speaking, rationing in the civilian sector is different from what you think of as a military "food ration". There wasn't a box with predefined contents to get you through the day. Availability of foodstuffs varied; the rationing was put into place to ensure that no-one got more than their fair share of limited supplies. As several foodstuffs were not rationed at all, and people were free (indeed encouraged) to complement their rations with home-grown vegetables, small livestock etc. "the post war ration" didn't exist and would only be a part of what was on the dinner table anyway.
Now that we clarified that "rationing" means allotting the right to buy certain foods to individual people instead of giving out a fixed "ration", we can look at what was rationed and supplied during war time and post war. This mostly oncludes basic food stuffs that were deemed essential, like bread and was kept up as deemed necessary for each item on that list:
One item of peculiar interest might be the bread:
Consumption of tea, sugar, cheese, and meat rose during the late 1950s and early 1960s and the increase in butter consumption was par- ticularly steep as people moved away from margarine. Among controlled items only fish, consumption of which had been exceptionally high during the late 1940s, registered a decline, milk remained stable, and egg con- sumption rose sharply. Simultaneously, potato consumption fell by about 15 per cent and that of bread by nearly a third between 1954 and 1965. The most striking example of a change in consumption after the lifting of controls was the dramatic switch away from brown bread. After the abolition of National Wheatmeal Bread in 1956, consumption of brown bread dropped close to zero in a matter of months and the white loaf again became the principal bread eaten in Britain.
Ina Zweiniger-Bargielowska: "Austerity in Britain Rationing, Controls, and
Consumption, 1939–1955", Oxford University Press, Oxford, New York, 2000, p 33.
And this is especially disturbing, as the UK government did not ration bread durign the war, but after the war, in order "to look needy" (Ina Zweiniger-Bargielowska: "Bread Rationing in Britain, July 1946–July 1948", Twentieth Century British History, Volume 4, Issue 1, 1 January 1993, Pages 57–85, DOI)
So going for the typical contents of the British "food ration" – i.e. in a typical diet – during the time of existing food rationing, you'll find darker bread. But you'll find most items that made the typicla British diet after 1955 already in pre-1955 diets. Just mostly in different quantitties and qualities.
Looking at the 1950s diet, we find typical calorie distributions, together with class differences:
Middle Working %
1932–5 3,275 2,859
1936–7 3,159 2,557
1944 2,403 2,387
1945 2,402 2,375
1946 2,336 2,307
1947 2,307 2,308
1950 2,506 2,468
1951 2,510 2,463
1956 2,597 2,615
1959 2,636 2,564
Sourced from Ina Zweiniger-Bargielowska: "Rationing, austerity and the Conservative party recovery after 1945", The Historical Journal, Volume 37, Issue 1 March 1994 , pp. 173-197 DOI
This wartime communism of more egalitarian food supply at the table is now painted as democratic and healthy even as sustainable consumption as Britain never had not enough food to begin with?
These are the official numbers. The private enterprise is usually called the black market were additional food items could be supplemented to the rationed foods. If anyone could afford prices for an unregulated private market, that is.
While in 1950 the criminal offenders on this private markets were still prosecuted for trading in each of the categories surveyed, by 1954 this was down to just "illegal slaughtering" and "meat", mainly, and a few carrots and potatoes traded privately, curiously.
To summarise how a "typical ration", that is diet, was constructed, from what was rationed and what was "digged" or "made do" during 1950, we might summarise it as:
we see the general pattern of more bread, more milk, red meat, relatively huge amounts of potatoes, copious amounts of tea, many greens, less fruits (and certainly not year-round but more for children than adults, per law) less poultry, less sugar, no junk food. (Compared to today baked beans make up 25% of total vegetable consumption in that group).
An even more colourful impression of diet features is in this list.
There is even an again politically motivated kind of experimental archaeology to recreate the circumstances and restrictions today:
Rations varied depending on supplies, but a typical weekly allowance per adult was 4oz of bacon or ham (about 110g), 2oz of butter (about 55g), 4oz of margarine, one fresh egg, 3 pints of milk, 8oz of sugar (about 220g). Babies and young children had priority for milk, but were also on half rations.
Keep calm and carry on with a 1950s menu