If you can make a phone call, surely you can do FaceTime Audio? 

josephhinvest: An easy way is to add a FaceTime Audio favourite to your Phone.app favourites on your iPhone.
Then on your Watch if you go to the Phone app and selects Favourites you can place the FaceTime Audio call directly.

Create the favourite entry on your iPhone by opening the Phone app, select Favourites, tap the “+” button. Select the contact name, then choose “Call” and then “FaceTime”. This will add a FaceTime Audio favourite. That should then be mirrored to your watch.

Cheers,
Joseph

Excellent will give it a go next playtime ..... or when I want to look like Dick Tracey!

josephhinvest: I often prefer to make a FaceTime Audio call instead of a cellular phone call as the audio quality seems VASTLY better. (iPhone X on Skinny mobile).

I would tend to agree with you but if you are calling on-network (i.e. Spark to Spark or Vodafone to Vodafone) or using VoLTE then the call quality is almost indistinguishable.