Macbook Pro 2017 not detecting any screen, hdmi or VGA
Well, I got a (very) hacky fix for this that may help other people so I'll detail it here.

I have a Samsung S10 phone. So I picked up the Duet Displays app that allows you to extend your PC / MAC to another device over Wifi. This meant I could use my S10 as a second screen. 

Next step was to connect the phone to the monitor and mirror the display.

That sort of works.

A slightly better option was that because it's a Samsung phone that means it has the DeX OS installed, and you can run the Duet Displays app within DeX. That gives me full-screen access on my monitor (albeit at not an ideal resolution, and sometimes lag too as it's over Wifi).

If you have an iPhone then I suppose Sidecar could also do the same configuration.

So there you go. Extend Mac desktop to phone. Connect phone to monitor.