Keith Barrett wrote:

I am wondering if any of the providers will allow the inclusive texts
and minutes but not allow any chargeable calls?

T-Mobile Fix-it used to. Not sure if it is still available, but that's
your best bet if it is.

Contract text bundles are cheaper, but only if you use enough of the bundle.

PAYG texts are around 6p each, though you can get PAYG bundles to make
them cheaper.

At 6p she'd need to send about 8 every day to get through £15 worth of
credit. Lots of teenagers do, of course, but is it necessary? They're a
very expensive way to chat.