Check out my username for British routes, some for older versions, some narrow gauge. My latest upload "Water Of Coate" is an upscaled representation of Swindon's local miniature railway and includes a session with multiple trains lapping that lasts over an hour.
And if your interest extends to narrow gauge, then the Ffestiniog/Welsh Highland by Malc - clam1952 - is a must.
Payware wise, the Settle & Carlisle is still worth a look and also includes a decent set of UK motive power and rolling stock assets.