It is quite simple, as above. they do want pictures of your consumer unit, if you have a isolation switch,
If it is just one mains cable and what rating is on the main fuse.
Just send in as many pictures of your supply, consumer unit, where you want the Ohme fitted and also they request an uninterrupted video of the consumer unit and the path to where you want the Ohme charger fitted.
If its a complicated install, they will send an engineer out to survey the site. But mostly its OK and they come and fit the charger quite quickly.