I think that would vary from area to area as the hospitals are run by Trusts and they all have an individual income. I'm not sure if the Govt have released figures for the whole of the UK
Recently NHS Sunderland CCG posted these posters around regarding paracetemol, , wasting as much as, apparently, £673,000, if it is given on prescription. I assume thats a rough estimate, but if you divide that by the 95 that happened in that year, it would work out at just over £7000 per HIP replacement surgery.
And thats just in Sunderland CCG area, not nationwide