In Flanders, some ads for privé ontvangst are actually escort ladies receiving you in (mostly) very discrete love hotels. As a client, it's practically the same as privé at her place.
Anyway, my advice:
Tell her on the phone that privé ontvangst is new for you (it once was for all of us

), talk about your wishes and her services, hours, prices,... After that it's
like a box of chocolates, you never know what you're gonna get. The surprise is part of the attraction. Go there without scenarios or all too specific plans. Just go along with the lady, but dare to ask, talk, be respectful and enjoy.
I can't imagine the worst that can possibly happen to you, but I guess you'll live.