I'd imagine he already has her mobile number....
Seriously, i'd ask her out for a drink first, for all you know she's just being polite as you're paying her for a service (steady!) she might just see you as a client she has to slap the "happy face" on for.
Sending her texts, out of the blue, in a sexual nature, will probably freak her out and result in you having to have a pony tail when she refuses to come to your house anymore.
And...she's 29, you sure she'll be interested in a boy of 19?