The fastest aubergines I have grown are Kaberi (mini fruit on compact plant) and Czech Early (larger fruit and more sprawling plant).
Obviously I am as about as far away from you as I could be without falling into the English Channel, but they might be worth a go.
Just a thought, but the tinfoil reflectors we all make for windowsill seedling growing in the spring. Would that be viable for your greenhouse? If the light intensity is weak, could you rig up a tinfoil covered cardboard panel in spring and/or autumn to help boost it. Maybe one of those emergency tinfoil blankets suspended from wire? Just thinking out loud but it might work
Forgot to add that I have a tiny chilli that originates in Hungary that I save seeds from each year. It is a birds eye type and the plants are easily small enough to sit on a windowsill inside. It is also very fast and had flowers and fruit on it way before anything else this year.
The fruits are fearsomely hot but you can hang the whole plant up by the roots to dry them and crumble into dishes as you need them. 1 if 2 is usually enough for me, but I am a whimp. Happy to send some seeds if you pm me your address