In terms of freight you should get a fair amount at Coatbridge Central. Not a particularly exciting station itself, with a measly 1tph passenger wise and serving the primordial sludge that is Coatbridge, but it lies on the Motherwell-Cumbernauld route that is used throughout the day by freight trains going up North (it's essentially a bypass to the East of Glasgow). Just to the North of the station, there's also a Freightliner container base, and a few miles South is Mossend terminal. In terms of units, a steady mix of 318s, 320s and maybe even 334s (i.e. the usual).
A quick look on RTT suggests about 1-2tph throughout a standard weekday (as far as freight goes), but it may be worth having a look over at the
Scot-Rail forums - plenty of gen on that site to keep you up to speed.
If you're looking for units, I'll second Patrick (14tph in each direction), Hyndland (same trains, better views/photo ops IMO). Paisley Gilmour Street has some freight passing through - not very much and mostly in the evening by the looks of things so it may be too late for you if you plan to get back to Nuneaton, but if you're in the right place at the right time there may be something to break the monotony of 380s.
