Well, pretty much another season of disappointment.
Really sorry to hear that. I've had some disappointments with things that I have never had a problem with before ... and updated my file notes to do things differently next year - for example, because it was warmer I have been keeping the greenhouse vents open a bit at night, which I have never done before and that (and the drought we had in May-July) has decreased humidity around cucumbers and they did not do at all well.
My advice may be no help, but in the hope that it might be here's some thoughts:
Carrots: I find them too hit & miss in the garden and now only grow in pots
Broad Beans Sutton: I grew "The Sutton" once, never again! The short stubby growth never really did enough to support what I would call "a crop" I plant Aquadulce (which are designed to overwinter) in late Winter [rather than over-Winter], and I think that makes for much stronger plants
Radish: I don't grow them, but DD's method with using a Cat Litter tray seems to be popular (details in a thread on here somewhere
)
French Beans: I grow Climbing French Beans. Their season is shorter than Runners (although mine started cropping a good couple of weeks before the Runners). The Dwarf ones I've grown tend to flop about and be a nuisance ... For Climbing Beans (and Runners too I think) worth planting a seed when you plant the plants out - so that you have a follow-on crop later in the season.
Courgette: "
Foliage now very pale yellow." Mine wind up covered in Mildew and looking pathetic by the end of the season - but having said that not this early except in a very wet season.
Cucumber: I think they are just plain "hard". I don't have too much trouble in the greenhouse (But mine have been a disaster this year) but not sure about outside.
slugs: lots of my plants decimated by slugs soon after planting - my fault for not putting anything down though. I'm going to give the chickens the run of the veg patch in the Winter and hope they mop up some of the parents etc.