150W LED should be fine in that tent you have. Maybe drop the lights lower and closer to the plants. Watch out for those plants in the dome though. They'll be cooked by tomorrow !
UK is getting into the winter cycle so you should have some nice cool air to feed into the tent. Use a fan and an open window or something inexpensive. Be creative !! Otherwise, don't worry about it too much
Your peppers should do fine as long as you give them plenty of love..... and light, and nutes at the right time, room to grow ( up-size the pots as they get bigger).
Last thought from me is that if you stick with the 150W LED, perhaps you should concentrate on ONE plant.... directly under your LED. You can experiment with having a a tent full of other plants, but focus on the ONE plant in the center. 150W isn't a very powerful light, so you shouldn't expect to have your tent full of amazing plants. You could place some other types of plants that require less light around the focus plant, and you could have nice results.
Good luck to you !
Happy Growing !