The United Kingdom is a country in Europe which is featured in Train Sim World. Currently, there are 6 routes featured in TSW, the Great Western Express, West Somerset Railway, Northern Trans-Pennine, Tees Valley Line, East Coastway and the Bakerloo Line
- British Rail - British Rail was the former nationalised operator of railways in Great Britain which operated from 1948 until the late 1990s when the network became franchised. British Rail has featured in two 1980s era routes for Train Sim World, Northern Trans-Pennine set in 1983, and the Tees Valley Line set in 1989.
- DB Cargo UK - DB Cargo UK is a major UK freight operator. Formerly known as EWS before being bought by Deutsche Bahn, the German national railway, it is featured in the Great Western Express and East Coastway routes.
- Great Western Railway - Great Western Railway is one of the privatised passenger rail operators in the UK. Its services are focused around London Paddington and the south-west of England. It is featured in the Great Western Express DLC.
- London Underground - Owned by TfL, London Underground operate services in and around London, creating the flow of people throughout the city. In TSW, it operates the Bakerloo Line from Elephant & Castle through to Harrow & Wealdstone.
- Southern - The privatised operator of the South Central franchise since 2001, Southern operates commuter and InterCity services along the mainly third rail routes south of London to cities such as Brighton. Southern is featured in the East Coastway route operating passenger services between Brighton, Eastbourne and Seaford.
- Great Western Express - Great Western Express was the first route set in the UK. It covers the Great Western Main Line between London and Reading and features three locomotives, the BR Class 43 HST, BR Class 66 and the BR Class 166.
- West Somerset Railway - The West Somerset Railway is a route that features the longest heritage railway in the UK. It covers the line between Minehead and Norton Fitzwarren and has 2 locomotives, the BR Class 09 and the BR Class 47.
- Northern Trans-Pennine - The Northern Trans-Pennine route is set in the 1980s when British Rail was still in charge of the railways in Britain. This is a historical route and covers the line between Leeds and Manchester Victoria via Huddersfield. It has 3 locomotives; the BR Class 45, the BR Class 47 and the BR Class 101.
- Tees Valley Line - This route covers the Tees Valley Line from Darlington to Saltburn, set in 1989 during the sectorisation of British Rail. Featuring many industrial areas, the route has a large freight focus, featuring the BR Class 37 for freight and the BR Class 08 for shunting. Also included is the BR Class 101 which is used for commuter services along the route.
- East Coastway - East Coastway covers the route between Brighton and Eastbourne via Lewes as well as the Seaford Branch. Primarily a passenger route, the BR Class 377 is featured, hauling all types of passenger services along the route. To cover freight services, the BR Class 66 is included in EWS livery.
- Bakerloo Line - This route goes through the heart of London, from Elephant & Castle through to Harrow & Wealdstone using 1972 Mark 2 Stock to make the 14-mile journey to operate commuter services.