I saw Dr Yau Thum at the Lister clinic following from a recommendation on here. My NK test was negative but I had other tests with them and subsequent treatment and was very pleased with my care there. Good luck OP wherever you choose.
Check out the thread TTC on prednisolone - full of ladies who've had NK cell treatment for recurrent miscarriage. They are now on thread no. 9. I thoroughly recommend Dr Shehata and New Life Clinic in Epsom. Good luck
Had a follow up appointment at St Mary's this morning (following 5th miscarriage just before Christmas) and the consultant suggested I might want to go for NK cell testing (privately) - with the caveat that it's a contentious one and other consultants at St Marys wouldn't agree.