Courgettes, marrows ans squashes can be planted now. Two plants are normally more than enough for most people. Plant three seeds two inches deep. Replace soil and cover with an up turned jam jar to increase the temperature and protect the seedlings. Also, four or so inches away, push an upturned squash bottle with its end cut off into the soil.
Courgettes suffer if their leaves get too wet and also like a lot of water.
The squash bottle will allow you to water safely and get the moisture to the plant's root. Thin the seedlings to just one once they germinate. Where there are gaps replant the seed. You should still be able to get new plants. Stake and tie in broad beans planted in previous months.