I have variable amounts of time on my plot, but have managed it even when doing full-time hours and pretty good commute.
You are on the right lines with the crops you are considering. You need stuff that doesn't need a lot of faff and also won't go over if you don't get to pick it for a week, although a quick fly-by to pick strawberries should be do-able. You can also uses mulches and weed control fabric to cut the work around crops.
Squash are very useful for keeping weeds down and are fine so long as you plant in a section of soil you have dug some decent compost or manure into. A good weekly soak is usually OK. I put wigwams of drying beans like borlotti beans in the mix and sweetcorn on the edges where I can get to it.
Cabbage and lettuce is also quite useful if you have a netted area or a crop tunnel it can be kept safe under. It needs little work and will happily get on with it. Tomatoes are surprisingly good as well. I grew Crimson Crush and Feline last year (both blight resistant) and got bags and bags of fruit.
For flowers I grow cosmos, sunflowers and dahlias, Sweet peas can be a bit of a pain as they go to seed every 5 minutes, but I tried helichrysum last year and they were good.
I also have no qualms about buying seedlings if mine fail, or I haven't had time to sow them. The garden centres have all the basics, but have a very boring selection of anything like squash, so it is worth growing your own seedings there. Annual flowers will usually be cosmos, perhaps calendula and sunflowers, but zinnias and cerinthe might be hard to find.
Upshot is that you can still get a lot out of your plot, so don't feel you can't manage it
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