@holidaylover, could you do online shopping? Even if you can't get a slot every week, maybe having an occasional online shop where you can choose what you want instead of relying on a family member might help?
Also, do you drive or does your OH drive? I've taken to going with my husband sometimes when he's shopping and waiting in the car. We had to stop off unexpectedly for something once when I was with him, and I felt quite overwhelmed by the sheer number of people & cars, which is why I've taken to going with him deliberately - I realised I was getting SO isolated that I was struggling with even seeing people at a distance!
I think many of us will find resuming normal life difficult when the time comes. I read a very helpful article about this at the end of the first lockdown. It was talking about the importance of little steps. So, for example, with shops, the first step might be walking past, the second might be walking in and out again, then you walk around a little more, then you go in to buy one item...and by gradually building it up, eventually you reach the point where you can just do your food shop as normal. The emphasis was on little steps that were achieveable, so that you don't try to do too much at once, be unable to cope and then feel terrible for 'failing'. You will get there - hopefully just a few more months to go.
