According to the figure, the weatherstrip (Item 2) is supplied By Peugeot together with the glass (Item A) and the support shim (Item 4). There are four variants of the glass, depending on whether you have rain sensor and heated or unheated windscreen.
If the glass is coming from a 3rd party source, without weatherstrip and support shim, I imagine it is expected that the original parts are re-used.
There is a 2nd hand glass plus weatherstrip currently on
Ebay uk, and there are several generic weatherstrip offerings on Ebay.