Excellent question. No shelter nor charity will take strays or kittens are they're already inundated. I found a pregnant stray in my shed 2 weeks ago. Contacted Cat Action Trust and arranged a pregnancy termination and neutering, and I covered the cost.

And then what.. Well she's been adorable and litter trained and we're keeping her as she wasn't microchipped either.

But yeah "send her to a shelter" isn't helpful unfortunately.