Thanks for your reply @ScoopUK.
Definitely I haven't come across any TI coaches like the guy in the video. Another Aussie ratbag.
Took the message "rhythm and relaxation" into the water this morning and by the end of the swim I seemed to be clipping along. I was in a lake with a 1km course marked by 100m buoys and although windy and choppy I timed some 100ms and it was promising. So focus is on rhythm and relaxation rather than stroke mechanics for the next while.