I've fostered 2 dogs via rescues working in Eastern Europe. Lovely dogs, with no issues. I was very upfront and told the rescues that I wasn't an experienced owner (don't have a dog but have looked after friends/family dogs) so that I needed dogs without any serious behavioural problems.
The 2 dogs were both lovely, no issues at all except needing recall training, which any dog would need with a new foster/owner. They were each with me for about 2 months (separately). The rescues I worked with don't have much money so I did insurance, paid for food, worming etc but I think that varies with different rescues.
If you haven't got a particular local rescue in mind, there are lots you can look at who do fostering nationwide (usually those working with foreign rescue dogs).
I'd also recommend joining the various FB groups that rescues run. It will give you a good idea of their "vibe", how they react to any issues, how communicative they are, what backup they'll give you (or owners) with any problems etc etc.
Have a look at Help Pozega Dogs, Balkan Underdogs, Black Retriever X - I'm sure others will recommend others. You could also look at the Cinnamon Trust. They have volunteer dogwalkers all over the UK, helping older/ill people who can't walk their dogs anymore, so it helps them keep their dogs at home.
I really enjoyed fostering and am just thinking about how to persuade my OH that I want to do it again!