Will create a significant space gap in larger stores. (Competitors Tesco, Asda run their own in store pharmacies).
Worth noting that most dispensing is for NHS prescription, i.e. a fixed service charge for handling the dispensing, controlled via government computer systems in store; some some other controlled non-prescription items sold at retail over the counter.
None of the supermarkets offer home delivery of prescriptions or controlled items. (Some of the other pharma chains and independents do–I think Lloyds may offer from standalone locations, and some locations of Boots–owned by Walgreens, also do).