The iconic British locomotive design (and the most common one) in the early 1840s was the 2-2-2 inside-cylinder tender loco. Each builder had their own unique features, but the general outline didn't vary too much across UK companies. This post gives some suggestions on ways to use the Dapol (ex-Airfix) Rocket kit to produce a generic single.
The model was built by Nigel Hill, who unfortunately isn't on RMWeb. There's still some work needed, especially fitting outside frames and hand