I no longer carry a SAK or Leatherman when visiting London. Too many of the places I go to have bag searches & metal detectors. The woman at the Royal Galleries at Buckingham Palace thought my tiny Leatherman Squirt was gorgeous , but I still had to collect it on the way out.
Boots have 2 x 125ml tubes of Colgate toothpaste for £4 so I stocked up on that.
Another advantage of being white, female and innocent looking to the point of naivety, and also carrying far too much stuff in my many pocketed bags just in case - no one has ever persisted far enough into the depths of my bag to find the SAK - I think it's been to all the major museums in London. The American customs did once find the scissors in my first aid kit on the way into the country, after I'd failed to wreak havoc with them on the plane, and didn't seem to know what to do with the information, since there was clearly no point in confiscating them at that stage. They were sure I was up to something since I didn't have any checked in baggage at all, but they couldn't work out what, and due to being W,F & IL, they gave up trying to figure it out. No one has ever tried to sell me weed either. Not even in Camden or Brixton. Or if they did try, i didn't notice.
I am trying to build up some stocks, but it's a bit awkward with not having a house. There are 6 + kgs of pasta and some tinned goods in storage in Leeds or somewhere though. I'm trying to buy a few extra tins or jars every shop.
I follow my grandmother's adage that one should always be well in hand with soap so have plenty of that. (Old soap lathers less, so lasts longer. Less of a problem in the super-hard water area in which I grew up than in the soft water of Sheffield where she did.) My mother had 23 bars of soap in her clothes drawers(that I saw, there may have been more) when we helped her pack up her house last year.
We have enough variety of camping stoves and their fuel to keep us going a while. Except the primus, but I've never used that so it will be last resort, it that's the only fuel I can procure.