You are going to have a fantastic time, just be ready for the heat if you are going in summer, make sure you go and visit Cleopatra beach. Pack loads of bikinis and make sure bf takes u to a nice hotel after meeting the family!
If they are non religious, you don't need to worry about anything, Antalya is a pretty modern place, people walk about in tiny vests and shorts with flip flops! Then coastal people have a culture of interacting with non Turks anyway... the fact they are used to tourists is a big bonus.
Like I said, just smile at the mum a lot, ask to help out, shoes off at the door, pretend you love her food even if its nasty... that kinda thing.. Hope u have a fab time n enjoy!