Stevie,

I live in Surrey, my chillies are still outdoors.
The varieties you are cultivating are not UK friendly, specially for the North.

(I buy my plants from Wilkinsons of all places, cheap and mostly OK.)

From the photos your plants appear to have not bushed out.

When 8-12" tall I cut the tops out, as you would with a tomato plant.
Attached are some photos of my plants.

Kind Regards
Brian