warp778

I have an old Megaw Z-4 Sailplane kit that I was given back in 1955 (see attachments). It was produced sometime in the late 1930s or mid 1940s after WWII. Megaw closed operations in 1949. All parts are there plus the full size plans. How do I find out or where can I go to find out the collector's value for this kit? I do want to sell it but I would like to get a fair price for it too.

Does anyone have any idea as to its worth?
Thanks for your help.