Ok. I've sorted out an issue in blue iris. It was still asking for authentication with the admin/password in the url. I have made my phone excluded (its fixed ip address) from needing authentication so can now go to the url below and it triggers the camera now.
So will now fix the ip of the esp8266 in the router setup, then spend some time to look more deeply into how to make the esp8266 go to this address now. Maybe start from scratch rather than copying and modifying someone else code as I have done above.
The url that worked was the following so I'm pretty confident I can work that out now... Always welcome to given advice, but I should probably make more of an effort and more mistakes before posted here I admit.