hi all, can I join please
not exactly allotment land here, just pots in the communal rear yard but worth a go 
courgettes rotting, HP, have you tried hand pollinating them? I've only got 2 surviving courgettes, one is nearly harvestable size
they are the two I hand pollinated after doing some research on the internet on why they might be rotting.
anyway other stuff, tomatoes starting to appear, will be interesting to see how they go, loads of lettuce, carrots were a disaster, pots in a bag, but late ones so got to wait until around september but not holding out too much hope. spinach has been a success, after managing to identify what it was
have got one of those plastic greenhouses, size of a shed, as part of the whole new to gardening and learning experience ... the sides flap against the shelves and knock all the seedlings onto the floor, resulting on me not knowing what anything is. problem solved by putting up some metalwork along the front of the shelves to stop stuff being knocked down.
slugs and snails are a bloody nuisance, I stamp on any i find.