Hey there, I can create the first head you'll need within 1 day and we can use that as a art test, following that, if you enjoy the results, we can do the others.
I would need about 5 hours for the fox head, that would be about 20 GBP by the standards you set on the project.
Most of the animals you've mentioned would take similar amounts of time. That would be about 200 GBP within 10 days for all of them if everything goes well.
You can see some of my work on my freelancer profile, and if you want, we can chat and setup this first head as the quality test, be it the bear as in the reference, or the fox as you mentioned.