Good news - he seems fine thismorning, a lot happier - i've purchased another big plant to cover the back. he is still sitting on the bottom for a little period but moves off again soon after.
I've cut the coconut, tried to scrape contents out but very hard, boiled it once already for about 30mins, so going to attempt to scrape out insides again... then sand it off properly.. once i've done this, will boiling it once more for about 30 more minutes be ok? I'm just going to lay it on it's side so he can literally go into it and rest in there if he wants to.