I did a google and had a look at the Gloucester Wildlife Trust site... they do a lot of events, but unfortunately most of them seem to be child-oriented. It might still be worth your time to get in touch and see if anyone has a garden regularly visited by foxes- they might be willing to let you come and photograph them.
Also another option might be to contact your nearest wildlife rescue centre- they also might know of a place. If you are near Tewkesbury, the Vale Wildlife Hospital is having an open day- you might be able to speak to someone there who could give you some ideas.
Just remember most people have learned to be very protective of 'their' fox visitors. Just yesterday I heard about a neighbour who is angry because of foxes coming into a garden next door to him. I have learned to not broadcast about our foxes because of people like him, because it might possibly put them in danger... there were a few incidents of dogs coming across poison presumably put out for foxes a few months ago very near to where I live. I deliberately let the trees and shrubs around our fences become thick and overgrown to prevent anyone looking over and seeing the foxes... I do all I can to keep them as safe as I can.
Unfortunately some folks regard urban foxes as a menace. Yes, they will rip open bin bags but, bin bags are just a food source to them.
They will take the odd cat, and I can understand the upset this will cause, but I think (and I have virtually no evidence to support this) it is unlikely for a fox to take on a healthy cat - the risks are too high.
When we had a cat the encounters between her and foxes, which we saw on the trail camera, indicated they were aware of each other but neither showed any aggression.
Hope you are successful in getting some photos of foxes, Monk. If you do, please post them on here.
Visit North London. We are awash with them!! We have one who regularly sunbathes on top of a neighbours car during the day. I have a den 10 metres from my garden and get very little sleep due to the youngsters falling out all night long!