I have a cousin who is a lawyer.
It feels (to this beginner) that there’s something missing from this sentence. For the translation, it feels like the Italian should be “Ho un cugino che è avvocato”.
Or am I being too English in my thinking? 
Hi, you reminded me of a phrase I learnt some time ago “Ho un cugino infirmiere”, I have a cousin who is a nurse. So “thinking Italian” I’m pretty sure the avvocato phrase is correct but as always, advice from a madrelingua is welcomed.
I have a cousin who is a lawyer.
So a year later, I subsequently learned that Italians often say “I am lawyer” or “I am nurse”, it’s just the done thing.
I guess I should be pleased I’m making some progress at least !
Buone notizie! The next step is when you start correcting yourself and recognising the Passato Remoto; -) Tutto è possibile👍