I have found a chap very local to me (a 15 minute walk at worst) who I will use to fit mine (he does these vids on youtube) so I won't be part of the group buy. It is important to me to get the thing fitted on the day I pick the car up so I need to go local.....
He seems a little unsure of how it works himself if I’m honest, he’s figuring it out as he goes along.
But I understand why you’d want it done on the day.