If you want to do this for fun, great. If you’re looking to make money, you’ll struggle. The hours/costs that go into kit production in this country can never be recovered at a sensible UK retail price. Modellers are so tight they squeak when they walk!
If you know someone in China that can manufacture everything and get it shipped over here, you may have a chance.
I know because a friend tried something very similar in the R/C world and all he achieved was costs.