I often grow garlic in the land vacated by potatoes, but the cloves don't go in until September or October. Now would be the right time to sow various Chinese and oriental greens which give a good crop right into winter. Mizuna and mibuna greens are very good as a cut and come again source of greens. Pak Choi type cabbages I find the best. You could also try American Cress, or Land Cress which gives you watercress quality greens (makes wonderful soup) but need reasonably damp conditions (Cumbria should be ideal).
An autumn crop of turnips would be excellent too, if you go for one of the small white varieties like Tokyo Top or the long turnip, De Croissy. It wouldn't be too late to grow small beet either like Chioggia (pink stripes) or my favourite, which is Burpees Golden (yellow beet, sweet like carrots).
Something else which is neglected but grown a lot in France is winter radishes, like Black Radish which make large white roots (with a black skin) but which taste like turnip if cooked.
Happy gardening.

Hi Peter take a look at my blog on Growing with the Moon in July to see what you can be planting now. Remember not to harvest all your early potatoes at once as the do not keep in the same way that main crop ones do. We just lift one plant at a time, use that up and then lift the next one. Other on her advocate not even doing that to start with - simply scraping around in the soil with your fingers and removing enough for the evening meal.