Hi, im in the uk too. you can get the b12 folic acid and ferratin tested in the aneamia profile test from genova. for the vitamin d, i used zrt labs, but not directly from them as they charged $20 shipping for a small kit which i felt extortianate. i got mine from here http://www.vitamind3uk.com/VitaminD_Home_Test.html
(i have no affiliation with them), same price test but free shipping, got the test kit ok and results took 3 weeks to arrive