Lima vans - correct, the CCT on the right is a BR Mk1 vehicle, mid 1950s onwards. The bogie van is fine apart from the BR bogies, which can be replaced with spares from Bachmann. 

Hornby - BR Mk1 brake third on the left, the POS (Post Office, Sorting) on the right is surprisingly accurate for an LMS vehicle apart from the bogies (BR again) and the toy operating bits. It's pretty close to one of the 57' designs albeit with some 60' features (the toilet window I think).  They did operate in ones and twos attached to passenger trains, not just in full TPOs. 

Dapol - Period 2 non-corridor lav composite, usually a suburban coach but could be used as a strengthener. The brake third is Period 3 and accurate. If you want to keep the Dapol bogies use brass pinpoints to keep the wheelsets in, otherwise swap for Bachmann LMS bogies. Both accurate but a bit basic by current standards. 

'Tri-ang' - Hornby 1980s vintage I believe, generic Period 3 LMS composite, kind of looks like all of them without being accurate for any of them. Generic bogies again. The heavy lines on the roof are correct, if poorly done on the Hornby ones and a bit overdone on the Airfix/Dapol ones. The lines on LMS coach roofs were prominent flat strips covering the butt joints between the roof panels, whereas those on most Mk1s were welds. 

Mainline - correct, Period 1 BTK, and an accurate model of it too although in the later livery. The other one is an Airfix/Dapol composite, I think, accurate if it is, but a bit light on underframe detail and it looks as though the windows might have been replaced, the Airfix/Dapol ones usually have a heavy prismatic effect. 

Finally - Hornby or possibly Tri-ang BR Mk1 brake third.      

As for what you could use, all the LMS coaches there are in the later 'simplified liveries, and the Period 3 coaches are suitable for 1933 onwards (dates vary for each diagram). The Precedents were almost gone by 1933, so really only the Mainline MK1 and the non-corridor composite out of that lot, and then perhaps only in the earlier fully lined livery. But it's your trainset and Rule 1 applies. Have a look at Ben Alder's Far North Line - he's got locos on there which only ever existed on paper, never mind didn't survive that long, and it's totally convincing. 

Thanks, @Wheatley.  I'll have to look into finding a stock of the Bachman bogies.   Problem I have here, stateside, is I get slapped with some serious shipping.    Occasionally takes me out of competition on otherwise good pricing.

Good to know I have at least three items out of this that will be functional.   Bogie swaps are a lot more manageable right now than whole kits.   Somehow 20+ years of 'static' kit building leaves me when I touch rolling stock.