Grow loads of things including Plums
Best to grow things for flavour IMO, easy to get tonnes of some things e.g. runner beans / tomatos but anything surplus either gets given away or composted.
Not exclusive but to give you an idea: Plums, Greengages, Damsons, Apples, Pears, Red and White currants, Red and White Gooseberries, Rhubarb, various beans, Leeks, carrots, Potatoes, Strawberries, raspberries, Celariac, Garlic,cucumber, courgettes, various salad leaves and of course Dandelions but not yet made coffee out of them or mixed with burdock, could go on but I'm sure this is boring most of you already.
Make a demijohn of Sloe Gin as well every few years...
If you want to do things in your conservatory suggest you grew a few chillies / peppers and tomatoes(cherry ones) to get you started.