I used to shop online for the same reasons but the Asda near us are terrible if you have a problem so after 3 consecutive deliveries that were wrong I gave up because they never sorted it without me shouting and screaming down the phone.
The 1st time the delivered 2 bags of food, it took me 3 days to get them to redeliver correctly, I might aswell have gone to the supermarket for it! Second time they forgot Nappies and all my meat was out of date the next day so I had to be refunded, third time they delivered me some elses Yorkshire Puds and I never got my frozen. The first time they delivered wrong I got a £10 discount and the second and third time I wasn't even called by the store to apologise or given anything to tempt me to use them again so i told the lady on the careline I wouldn't ever use Asda again lol.
About a month ago I got a letter saying that I hadn't used them in a while and some money off vouchers - I just chucked them in the bin.
I go to Morrisons now as my
SIL works there and she gave me her staff discount card so I get 10% off my shopping which really helps
I plan out all my meals for the week now and just get what I need and make a list and stick to it. If there is something on offer, I will get it if it's something I use all the time.
I probably would still use the online if I hadn't had so many problems - I like Sainsbury's but it's just far too expensive and they don't charge you for substitutes like Asda do, you have to pay how much they cost, not what you originally wanted cost - so you can end up paying something stupid for a loaf of bread because they didn't have what you wanted.