Oil leak from behind WUR on late DX

Hi everyone. Not posted for awhile as the Sportline has been undergoing a DIY engine rebuild. I've so far done circa 250 miles since a top and bottom end rebuild and Sod's law the only seal I forgot to change has developed a slight weep.
It's coming from behind the aluminium plate that the WUR bolts to and I'm not sure which gasket/seal I need to order. Does anyone have an idea?
Also, what's actually behind the aforementioned plate? Is it a breather tap off for other engine variants ie Audi Dz maybe?

thanks in advance

its a blank for the fuel pump hole used for carb engines, and on the kjet cars also the mount for the wur as you know. the seal behind it is 049127311, NLA from VW but available elsewhere:
https://www.vwheritage…-mk2-golf-1800cc-engines/

That's ace. Thanks for the link. Helpful and knowledgeable as always. 
Thanks

aha nice one i think i have the same problem.

Nice one Mr rubjonny.
Andy