I work at an Asda Superstore (large supermarket) who are taking similar steps to similarly sized Tesco's/Morrisons/Sainsbury's etc.
As many have said there will be measures to control number of people in the store and how you move around it. No matter how infuriating it gets please do follow the arrows. It helps you to keep a safe distance from customers and staff and will help you see anyone oncoming who isn't following it and allow you to try and move out of their way. Do not ask other customers to follow the arrows as staff have been getting abuse and I wouldn't want a customer to be on the receiving end of it.
Please remember staff can't always move out of your way, if you don't feel they're aware of your presence just hang back and if needed just say hello. Try and give us 2m distance and a bit of extra time. We're coming into contact with potentially 100's of people on shift and want to protect ourselves, families and customers.
Your shop will take longer if you're following the 2m advice, be prepared to not just be able to get in and out. From experience the quietest times seems to be weekdays from about 11am onwards. There was still some panic buying at my store after payday last weekend but stocks were recovering well by Wednesday.
I don't know if Tesco offer a 'scan and go' option but it's worth looking into it. All colleagues have been asked to use the mobile app to ensure we can get through the checkouts fast and not add to the queues. It also minimises our contact with other people.
Lastly, just buy what you need. Just because you can buy 3 packs of 24 toilet roll doesn't mean you should (not suggesting you would but there might be some here), there is plenty of stock coming into stores and if we all bought what we needed there would be enough to go around.