From the link -
Pay with card, PayPal, or using your Online Business Account
Drop off at a convenient location:
Royal Mail Customer Service Point
Post Office® branch (except Tracked 24/48 packages)
Postbox drop-off (except tracked items, or items requiring a signature)
No mention of door to door.
So its not really an extra service, just a different way of paying, possibly more convenient for somebody, probably not for a "normal" customer.
Our local parcels collection center went from a convenient (for the customer) spot in the middle of town, close to almost every bus service, to a spot out on the edge of town that requires almost everybody using public transport to plan a days expedition. And for drivers, a site that is unfindable for a satnav, which guides you to the back wall on a "no stopping" bit of main road about a quarter of a mile from the turn off.