UK: Royal Mail Collection service from stores

Does anyone in the UK have experience in using the fairly new Royal Mail collection from store service? (This is where the normal roundsperson will pick up labelled outbound when they stop by to deliver the mail, at whatever time they normally get to the store)

I am looking into it and have found there may be some operational challenges around accurately measuring transit time and also some complexity on pick up process in store.

As a company, we already have a contract with Royal mail and fixed Royal Mail collections (for various speeds of service) from our warehouse. The warehouse collection is on a trailer swap basis–we fill during the day and Royal Mail bring an empty trailer/trailer with returns at end of day and take away the filled one. This includes having Royal Mail integrated via our carrier management system for label generation (with tracking numbers) and manifesting.