Got very fed up at the start of lockdown with Tesco as no slots available at all for several weeks. We had done literally all our grocery shopping there for years. I actually rang up their customer service and said you can look at my Tesco Clubcard to see how much I spend with you, but I can‘t get a slot, but just got the brush-off. No Sainsbury’s, Waitrose, Asda or Ocado in this area. There is an M&S, but when they advertised Ocado deliveries, I rang up and they said not in your area. Then Morrison’s started doing deliveries. Hurrah! A slot every week, cheaper than Tesco, lovely delivery drivers. The only problem is, you can‘t opt out ofsubstitutions, and there are some very odd ones, plus some that ought to be made but aren‘t, eg no bread or milk sent when specific type ordered is unavailable. However, a list of substitutions is sent before delivery, and any you reject are taken back and refunded.
Can‘t comment on flats, sorry, as we live in a house, but they always deliver up our awkward long drive