NIS is now an ATS testing centre.
For the BMAT – BMAT is a 2-hour, pen-and-paper test divided into three sections (Section 1: Aptitude and Skills, Section 2: Scientific Knowledge and Applications, Section 3: Writing Task) You can find out more about the BMAT and if you might need to take it here: 
For the Thinking Skills Assessment, required for Oxbridge, Leiden and UCL, click here: http://www.admissionstestingservice.org/for-test-takers/thinking-skills-assessment/