Charming and helpful host with a wonderful flat. It is furnished and kitted out to a very high standard. Would highly recommend and would stay again. Well located for the tram and U-Bahn.
Christoph very kindly arranged a taxi to get us back to Tegel on leaving.
Tips from me are to make the effort to go up the road to the REWE supermarket (in UK terms, just like Waitrose) and the restaurants Auszeit and Friedrich. And use the BVG app for buying tickets - worked really well.