Where to get 3alpha-diol G test in London?

I’m finally getting the recommended short list of tests done to get a clearer picture of how PFS is affecting me. I’m getting half of them done on the NHS but need to get the some done privately.

My problem is that I cannot find anywhere that will perform the 3alpha-diol G test. Where can I get this done in London, UK?

Also since the recommended short list hasn’t been updated for some while are there any other tests that people feel are essential and that I should also include?