Hello Roger and welcome.
I stopped growing sweet potatoes undercover because of the space they grabbed, for low yields. You have done well to garner some harvest in Lancashire. Chitting is a good plan to save money.
I pinched out aubergines this year and found them easier to manage, on two stems in fact, harvests were good. But they grow fine without pruning! It took less time than for tomatoes.
Peppers, I am unsure. If unpruned they sprawl and then developing fruits pull down and snap the stem, so they need constant tying. Maybe someone else has a better way.
