Ah, I see. Somehow I thought the wheel button was for the cars system only, not to connect to Android Auto. I have rarely used the onboard satnav, I mainly use Google Maps and ABRP for longer journeys (I have a dongle in the OBD port full-time).
I have to go from Swansea to Newport today, 70-odd miles each way so no need for ABRP. I will experiment with this.
FYI, if I have AA connected and I say, when stationary, Hey Google, wait for response, what's the weather today, it will work perfectly. Once I am moving however (which is when you need the handsfree) I get no response.