Current no setup fee is a 'promotion' so may be time dependent as to when the OP decides to join VM as to whether booking a tech in advance costs or not
The legal stuff - No setup fee
This promotion means you won’t pay the usual setup fee of £35. No setup fee is available on all bundles, broadband & phone, and broadband only packages. If you can set up using a QuickStart self-install pack, but choose to use an engineer for the installation, you’ll still be charged £30 for this service.
Outside of the promotion, they may have to pay a fee of £35 to get a tech out because the previous occupier chopped the VM cables (which is a sort of indirect 'damaged equipment charge')
(assumes they might want to prioritise the possibility of a quicker and easier installation by booking a tech first of all over the possibility of a failed Quick Start, a delay waiting for a free VM tech visit and the dubious possibility of maybe getting some compo)