I'm a native German speaker currently working as an Au pair in Clapham South. I would be more than happy to help you out by chatting with your children in German in a fun, playful way.
@betsyboop, I'd also love to help your son. I have lots of experience sharing my language/culture with the children that I work with.
Please feel free to reach out to me if interested, my number is 07481461568.