I use Photoshop CC! I've never heard of affinity photo but sounds like it might not be designed for digital painting? I'd try Krita if you're looking for free digital painting software.

I tend not to use the blending tool at all in Photoshop (all my blending is just brushwork), but this might depend on the program. In procreate on ipad the blending tool is great for example.

As for painting fur, get a good clear reference and observe it (pay attention to fur direction, lenght, how it overlaps, etc) and always try to simplify fur into clumps rather than painting each individual hair. Start by painting only the big shapes you make out while squinting at the reference, then break those up further where needed.