I have heard the rumblings too even though I'm on the far side of "the pond." I hope it doesn't happen since there would probably be a worldwide economic panic and depression that would make 2008 and 1929 look mild by comparison.

In answer to your question:
Well, food, water, fuel, batteries, medicine, and first aid supplies certainly.

If your cooking, lighting, and heating systems are dependent on a a central facility, then invest in means to supply them independently.

You may want to make a list of things you consume in a typical month: everything from apples to Ziploc bags. Perhaps stock up on a few.

HJ