Hi Alan!
Welcome to gardening and welcome to Germany, too! Where abouts are you? I live in the Forest of Oden (Odenwald) between Frankfurt and Heidelberg and run a market garden there. So any language problems can be solved!
Black polythene can be sourced as “Silofolie” (black or green on the one side and white on the other) in Germany, compost is “Kompost”, green waste compost is “Grüngutkompost” or “Grünschnittkompost” and mulch is “Mulch”.
And you can deem yourself lucky, because in Germany composting green and household waste is the standard, so the chance of finding somewere to buy in compost close by and relatively cheaply is quite good.
