Dado trunking cover / capping (Allerton BD15)

I'm looking for around 1metre of the central capping/cover for Bendex dado trunking for Allerton Men's Shed (Registered charity).
We have fitted some pre-used dado trunking that was donated to us, but we are a bit short of the cover panel.
We need around 1metre, it could be made up of a few smaller bits.
If you have any offcuts lying around, they would be greatly appreciated so we can finish off our electrical installation, ready to be certified.