I lived through the fifties, OP, so here's an example of what we ate - note, children and adults ate the same food, just different quantities.
Breakfast - boiled/scrambled egg, half slice toast with butter. Milk for children, tea for adults (no sugar, often no milk). We did have porridge if we wanted it (before the boiled egg) but it was made the Scottish way, with water and a little salt/no sugar added, so I tended to miss that.
Lunch - home made (thick) lentil soup with butter beans, a few slices of cheese. Milk or tea or water to drink. One slice of bread and butter (probably half again, for a child).
An apple when home at 4pm.
Dinner - meat (beef or lamb), potatoes, root vegetables, cabbage (lightly cooked, and chopped with butter).
Followed by pudding every night - some kind of home-baked sponge (eg Eve's Pudding) or tart with custard.
When we were older, we'd sometimes need topping up before bed - so that would be a slice of toasted cheese and more milk.
No crisps, no chips, no chocolate or sweets except on Fridays when we were taken for a two-hour walk on summer's evenings after dinner. We were allowed one small bar of chocolate (the sort of thing people would buy for a toddler now) to eat half-way round. In summer we'd also have the occasional (ie once a week) ice cream cone.
My family members were all thin by today's standards, adults and children. We didn't have a car until the mid-50s, and even then my mother shopped daily on foot - the car was only used for "outings". Going to the city meant a half hour brisk walk to the train station, and half an hour uphill when one came back laden with parcels.
Oh, and in 1950s Scotland - no booze for women!
Good luck.