I hope thinngs work out,Lynne. While Britain doesn't have a rabies issue, is there a problem with distemper? (which may manifest in some of the same symptoms as you describe.)
I like foxes they are beautiful animals but I also mind what my father always advised that generally wild animals retain a wild core and that will likely show up as he grows ill. Heavy gloves is a sensible precaution.
Again I hope all works out and you can tend to the critter or at least make his last days a bit more comfortable. Neil