Meatshake, most shops have made their new rules really clear. There's likely to be an employee outside the shop, or a written sign.
If you can't see a queue, you can head straight in.
If there is a queue, it will be obvious where to join at the back and signs telling you to keep 2m from the person in front/behind.
Inside, if there's a one way system, it'll be marked by arrows on the floor.
At tills and counters, there will be plexiglass between you and the staff member, and possibly a line on the floor to stand behind so that you're not too close.
Some places have relaxed the rules on having someone with you, just not two trolleys.
I think the pp's advice to call first if you're anxious is a good one.
Please don't let all of this put you off getting what you need.