It’s great that you’ve given him CC, since it has the fibers his gut needs.
Could you order Oxbow Timothy hay online?
Sometimes a bunny will eat more hay if you top it off with sth like dried dandelion greens etc. Dried leaves can be bought in pet stores. You can also dry leaves and herbs yourself, like mint, or even sprinkle dried mint flakes sold as mint tea on the hay. Chamomille may also work. Once you get the bunny to have a little taste of the hay, it may find that it’s not so bad after all and eat more of it.
I also find that serving little wads of hay thoughout the day, not a whole big bunch at once, even hand-feeding it, may entice the bunny to eat more of it.
You can massage his tummy a little to help the gut moving. This is a nice video on how to do it:
https://www.youtube.com/watch?v=JnuxGLa2reg
If he’s not eating properly chances are he doesn’t drink enough either, so you may have to syringe him water. I hear there’s a heat-wave about to decend on northern Europe, if it gets really hot, he may need extra water.