Contact your local council to offer the space and let them know what you can offer.

I wouldn’t assume anyone would take it up though unless the UK’s policy changes dramatically. We don’t seem to be letting many people come, and those that do will have a family link. Most will come and stay with said family, and any cases where there isn’t room the council usually has options it is more familiar with to house them in.

Donating money to a bigger organisation that is helping on the ground or at the border might be more useful. You could also see if there is a local Ukrainian community centre anywhere near you and ask if there is anything you can offer them. The one near us has been accepting donations of very specific things, like nappies in size whatever, and old mobile phones.