Many home contents policies do cover model railway items, but always check the value ! - many of us do not know the actual value of our collection (& don't forget the replacement value of the actual layout if any) - in many cases it could take the whole contents value well over the cover taken out !
The other thing to be careful of is the word "collection" - some companies would regard your model railway items as a "collection" & therefore subject to separate notification - still covered, but they want to know about it.
In any case, be on the safe side & document your collection, backed up by some photos. Will be very useful in the event of having a claim.