Re: Why pay fees at all?
As other people have already said - there is no "UK Police Force" - there's 43 in England, PSNI, Police Scotland and I'm not sure about Wales.
There isn't a single "NHS" to buy things. In my county, there is the Clinical Commissioning Group (admin types who buy in services), 2 Acute hospital trusts (1 in the north of the county, one in the south), and shedloads of individual GP practices. All of whom negotiate and purchase for themselves only. Some practices may have 2 or 3 GPs, some practices may have 4 or 5 sites each with 4 or 5 GPs. Most use one of three different systems, so no volume here.
Ditto Education - 350 odd schools, mostly working on their own - OK, they get good deals from MS, but it's not like there is any joined up thinking here!
Whilst it would be nice to have someone negotiate the volume discounts, at the moment, there are too many egos and too much chance of a turfwar for it to happen.