I found the first spider in my garage in February, I got a couple of low quality pics on my phone before it scuttled away and I never saw it since, I think it was about the size of a finger nail, and a slight red tint on the abdomen. Then today I was getting my neighbour's lawn mower from their garage (completely separate and at least 30m away from mine) and the second spider crawled out from inside right next to my hand. While taking photos a second came out too. I would say they were between 15-20mm. Inside the mower were lots of little white balls of what looked like web? I also noticed little dimples on their backs.
I did some searching on the internet and can't decide whether these were cave spiders or false widows. I think the first spider was different to the second two.
Just good old Steatoda grossa - arguably the most widow-like of the six UK False Widow species. It's a harmless species - very infrequently implicated in bites to people. The white balls are her egg sacks.