I happened to see this today on the Mayor of London's Facebook page, and it looks really cool and interesting. It just opened 3 days ago and it gives people a behind-the-scenes look at the V&A’s treasures that are usually stored away. It's free, you don't have to book ahead, and there are 4 levels (equivalent to the size of 30+ basketball courts) filled with over half million creative works from the V&A. This explains it pretty well: https://www.vam.ac.uk/articles/about-va-east-storehouse but here is another article that gives more detail. https://www.vam.ac.uk/east/storehouse/visit#things-to-see-and-do
It sounds wonderful and I'm so sad I can't go right now.
You can also make an appointment to see any object there that you like and it's open seven days a week. It's called Order an Object. I'm fascinated by this whole concept! https://www.vam.ac.uk/info/order-an-object