On the papers - to be sold at auction she had to have papers - there should be a town - North Somerset is the county - most roads lead to Bristol. The address you have quoted doesn't give enough detail.
There should be a town and a postal code.
You need a post code number to get more info.
Has the horse been chipped?
On the passport is there a vet's name?
My guess is that her owners went broke and there are a lot of people going broke these days. Seems as though the horse has done well to find you.
Look after her
You'll find out with time and patience all you need to know about her. The horse will tell you.
Let her start with a clean sheet.
Get her vetted, have her teeth checked. Worm her.
Give her a flu jab. Buy her a water proof outdoor coat
Teach her to speak Dutch and to walk on the wrong side of the road.
And watch out for when the Gypsies are about - they will love her.
Best of luck with your new horse and welcome to the Forum.