Yes autumn is more fine than summer… good for fennel, but sooner or later the bulbs may elongate, after swelling, so I would start harvesting one at a time. Also they perish in frost.
I have given up growing Butternut for the reasons you describe, it needs the kind of warmth you get in south east Britain, whereas we are cooler in the south west. Nonetheless I have harvested some Kuri squash already.
Pinching out the leaders does not help as they just make new ones, in my experience.
I think you may have an unproductive variety of courgette, what is it? Feeding and watering makes a good variety give lots of fruit.
