Slightly later than the CF steam era, but there was a Bus 639 that went along York Way, then turning right (eastwards), then left (northwards) onto the Caledonian Road, and returning (westwards) via Market Road (which is modelled; the parallel Brewery Road is not). Page with map:
https://www.londonbuses.co.uk/_routes/withdrawn/639.html
However, there would be weird scale (and clearance) issues at the top of Copenhagen Fields where Market Road/York Road intersect requiring one of those dynamically resizing Harry Potter Knightbuses!
Perhaps a solution could be to make use of the large width afforded by the North London Line bridge over York Road and "disappear" under the bridge (or via the immediately-following cul-de-sac) into the backdrop. Presumably real estate is cheaper on the backside for a corresponding bus depot/turning loop. This would create an allusion to the disappearing act performed under the post-1937 Waterloo Bridge, with trams entering the southern end of the Kingsway Tram Subway:
en.wikipedia.org/wiki/Kingsway_tramway_subway#Waterloo_Bridge_rebuilding
Using the NLL bridge as cover would keep bus/vehicle traffic captive within the ~1:152 zone. Technology-wise, choices are probably CarSystem-style (self-propelled vehicle, following iron wire, complex vehicles), or Magnorail-style (moving chain, occasional magnets, complex infrastructure, baseboard joints...; but existing resin models would work).