Taking in a flatmate

[aolangs]

Hello!
Glad I found you again as I used to dip in to TTG and was sad to see it had gone.
I'm hoping someone here can give me advice on a couple of aspects of taking in a flatmate.
Key points:
1. I'm the owner, not a tenant, so a sub-letting agreement doesn't seem suitable.
2. I'm letting one room (with use of k&b), and retaining one room for my own (occasional) use.
3. We're both fluent in English, my prospective flatmate is learning German, so I'd prefer it if we could use an English-language contract. Is this acceptable in German law?
All I can find are tenancy agreements or sub-letting agreements, and I'm not sure either quite meets the case. I would see the situation as similar to a British lodger, who rents a room and use of the property from a live-in landlord. Does Germany provide for this in law? Would it be a Wohngemeinschaft? Could I use a UK lodger agreement as a template? (I don't think they refer specifically to UK legislation except implicitly in the definition of the term 'lodger'.)
Massive thanks for any help!
Alison

[PandaMunich]

Just use this contract: https://www.stwgi.de/assets/public/down ... ertrag.pdf

[aolangs]

Brilliant! Thanks so much PandaMunich!
I'm a translator so I can make up a translation for their reference before signing (which of course they should check with a friend/Google. Preferably a friend. I've seen what AI can do and I wouldn't rely on it.).