Update -
I’ve finally solved my initial problem and reason for posting this topic in the first place.
I’ve downloaded the “Inverter” android app and paid the extra £10 for control access on it. It’s been running a couple of days now and I can get it to automate a timed discharge to the grid at a time of my choosing and then put itself back into Eco mode afterwards. 
My inverter is one of the early models hence the discharge timings as listed above didn’t work unfortunately but the app allows scheduling the Eco mode on and off at certain times, so you have to schedule it to switch eco off, then do the discharge, then eco back on afterwards. It took a bit of getting my head around the app settings but I seem to have it sussed out now.
I may well end up switching to Flux at some point (Maybe just over the summer months) and knowing that I now have the ability to do a timed discharge will potentially allow me to get a little more payback out of my extra battery.
Also handy to have the app as security in case (if or when) the G.E. server goes down, I should still have local control.
I dragged my retired android phone out of the drawer, got it powered up and will just keep it plugged in at home and running the Inverter app. It needs constant wi-fi connection to talk to the router, so I can’t have the app running on my main phone as it won’t work if I’m away from the house.
As for Axle, I signed up over a week ago and so far they’ve only run one event on my inverter but it’s early days…
Cheers All 