John Cutler
My advice would be to build a short piece of plain track using ply sleepers, C&L chairs and EMGS rail.
Butanone may not join ply with plastic chairs as strongly as plastic to plastic but an eminent EMGS member (Douglas Smith?) tested such joints to destruction and concluded that for our purposes they were not much different in strength.
One advantage of ply sleepers is that you can pre-colour them with ink or dye before assembly, as recommended by Ian Rice. Another, I find, is that if one hashes the alignment, it is possible to insert a sharp blade betwixt chair and ply and break the Butanone bond fairly cleanly to move/remove the chair (yes, you can conclude I bodge my track-laying!).
Do not underestimate the hassle in colouring the trackwork; use the test piece to discover what you need to do.
I also suggest you try Exactoscale chairs as well as C&L.The range is different with more railway company variations.
I recommend you buy “An Approach to Building Finescale Track in 4mm” by Iain Rice (Wild Swan).
Although it is dated, most of the content is still relevant.
Good Luck!
John C