I think the problem with courgettes is boiling them. Just come back from holiday and they had courgettes described as saute every day. But they were boiled - edible just but very dull. For me courgettes have to be sweated slowly in butter (with onion if you like them: I do not). Then covered with sliced tomato and herbs to taste and topped with thin layer of cheese and then grilled or microwaved.
Those I planted in April disappeared, thought to start with it was slugs, but some of them turned up elsewhere on the site, looks like they walked.
Is it too early to grow lettuce on the windowsill.