Cheers Doug, can’t seem to find a 34t one (of any brand) anywhere.

I think you will just have to wait. At a guess, since Shimano don’t endorse aftermarket rings, most of the manufacturers will likely have to wait until the retail cranks become available to get a set for development and testing of their rings, so given the cranks are just available in the last few weeks, it will take a bit longer.
Absolute Black say theirs should be up next week, they will also have a slightly cheaper version available via CRC. http://www.chainreactioncycles.com/black-by-absoluteblack-narrow-wide-oval-xt-m8000-chainring/rp-prod139806