There is more here than the comments, so don't give up. Am look for compact in 0, where small is very large!
For me it will be Huddersfax High Level, rather inspired by Halifax St Pauls, a long lingering NER/GNR/LNW joint branch with a dilapidated wooden building and lingering signals, including an NER slotted type survivor with a 2 Road Eastern Region Glasshouses depot. Loco hauled will be short, replacing DMUs as per the NER on the Middlesborough-Sunderland-Newcastle-Carlisle in the great DMU crisis. 3 coach 31,37,45,47, surely a 40/46 wriggled on too?And they need an 08 shunter release(Buxton had 08s) Household coal and TTA household fuel lingered on in many spots until 1978-84. This was when many coaling facilities closed, there were many examples included Layerthorpe,Malton,Scarboro, Whitby,Harrogate,Leyburn,Bedale, This means a lot of inspiration from the following almost lost but lived near places can be added in and are good suggestions
Buxton DMUs and DPUs pushing them up the hill
Ashington and Blyth Cambois( this was a TMD, no allocation but full of 37s and 56s) also saw 60s
Whitby small terminus, mostly DMUs, odd special, and coal saw 40s 31s 20s
Redmire Stone and DMU specials saw 20s,31s,37s,40s,47s,60s
York LAyerthorpe Branch again saw Rowntrees DMU and choc, whisky, cement,coal,oil with 03/08/20/25/31 and a 40/46/47 specials, and the 04s on the DVLR, but most often a bonnet first 20.
Clayton Branch(now a steam line) DMUS and coal trains of many 40,45/0,31 maybe more
Harrogate line had shorter locos with Deltics ,31/4(a specific pool) 40,45,47 on split Yorkshire Pulmman, 2 wagon steel trains to Starbeck and short military trains to Starbeck
Warcop as we get more 25s,40s,46,26&27 on Troop trains, but it is North Eastern
PEnistone Goods, coal until the Woodhead closure, but diesel operated.
Hitchin TMD is the glasshouse aka Heljan, again no formal allocation but was home to 31s and the baby Deltics., and Tinsley running shed, with Class 13s amonst many
So loc wise, the full choice would be 03/08/13/20s/25s/26/27/31/37/40/45/46/47/55/56
DMU wise then, we have possibly 101/104/108/110/DPU as a staple, earlier losses the Derby units, 100/105 hybrid,114/ 120s, TPE 123/124. The Eastern region was for many years a green Derby type bubble car (until 1973) then a Dapol Bubble car-
So the whole thing needs perhaps a CLass 122, Class 03 or 08 , A CLass 20/ 25, or a 31 and a 40,, maybe specials if in 00 45.55 in 1978, or say later 1983 a Class 122, Class 08, 20, 25 31/4, 46
And late 80s more color a Class 141 in Green A 20 in Thornaby bling 37/4 in Buxton colours, a 47 in some large logo but the freight will have gone by now, save depot transfers and fuel