Congratulations on coming through chemotherapy and getting better.
Here are some ideas for small things to eat that are delicious and easy to prepare:
Spreads that you can out onto a slice of toast or have with some slices if cucumber and pepper, eg humous, smoked fish pate (fillet of smoked mackerel or some smoked salmon, blended with full fat cream cheese, a squeeze of lemon and some black pepper), peanut butter (good with apple), egg or tuna mayo, pate or rillettes (I like duck liver pate, available from French delis)
Eggs - I like to do single egg omelettes with frozen spinach (1 knob microwaved and stirred into an egg), fried in butter with a scattering of grated Parmesan. Takes 3 minutes. Also lovely with mushrooms fried with a bit of garlic.
Smoothies - try banana, almonds and dates with full fat milk, or any kind of fruit with creamy full fat yoghurt. A bag of frozen red berries is useful here, as is a carton of yummy apple juice to dilute.
Soup - I'd buy these and freeze what you don't want. New Covent Garden has nice flavours, eg Thai chicken.
Ready meals - as posh as you can. Pieminster pies are delicious. I think Higgidy does nice quiches.
Small baked potatoes. I like mine with cottage cheese and black pepper.
Snacks you can have straight from the fridge: yoghurts, frankfurters (or other cooked sausages) dipped in American mustard, cheese, chocolate mousse.
I hope some of these sound appealing. I think much can be done by shopping thoughtfully. Good luck.