Help with Mothercare Spin and Britax car seat!

[mia8]

Wondering if anyone has had a Mothercare Spin and could help!

I got the Spin second hand, gorgeous condition, love it! A friend gave a Britax car seat as I would only trust a friend who said it hasn't been in an accident and wouldn't buy a second hand one otherwise.

On the Mothercare website, it sells adaptors for a "Britax Baby-Safe Plus SHR I or II infant car seats" and I've just realised my friend gave me a "Britax Rock A Tot (R-A-Tot) Plus SI".

Does this mean the adaptor won't work? Do you have to get a specific adaptor for the buggy and the car seat?

Sorry - new mum and not sure what it all means, just want my baby to be safe! Thnk you!