Not much will grow this late in season from seed, but if you get cheap plants (garden centres may sell off as it's late) some things may possibly do something.
Seed sowing now and into autumn for growing next year might be possible.
The VERY EASIEST thing to grow is courgettes; sow seed in pots next spring, plant out in May; harvest July/Aug onwards. BUT - the plants get VERY large, so maybe you won't have room. Keep picking to keep them coming; turn into marrows if left too long.
Strawberries are a lovely thing to have, and you can plant now for next year:
www.bbc.co.uk/gardening/basics/techniques/growfruitandveg_strawberries1.shtml
only need straw or similar to keep fruits off ground when they form, and net over them if you have trouble with birds.
Raspberries are nice too, but will need some form of support, and the canes need pruning; probably come in summer or autumn fruiting varieties.
If there are any gardening clubs, or friendly enthusiasts near you, they will probably advise/help, and might share plants with you.
On-line, there are plenty of dedicated sites for almost every kind of plant, so look there for more detailed help.