I can touch-type in Russian and English layouts.

My favorite keyboard is British up to the point of me specifically picking a laptop/physical keyboard with a British layout.

Just learn both and you'll be OK.

Lucky for you, that you managed to learn to touch type on the different layouts. It might help though, that Russian and English are entirely different layouts. The problem with German and English layouts is, that they are mostly identical, and only about 10% of them differ. This makes it very difficult to master both layouts at the same time. I tried it for a while, when I had to use an English layout temporarily. My experience was, that it thoroughly made my typing worse on both layouts.

I've got friends who used the phonetic version of Russian keyboard where about 80-90% of the letters are going to be similar phonetically. All of them can touch-type by now.

The thing with touch-typing is that you don't think so you have to go through a period of discomfort.

I am very proficient with touch typing. But in my experience, mixing German and English keyboards erroded my skills considerably.

I regularly switch between American and French layouts. I don't think it's particularly hard.

Edit: If that wasn't clear, I meant that I touch-type on both layouts quite easily.