UK medical student here originally from Malaysia (and was also a regular in the Medicine sub of Thestudentroom). A good UKCAT score would be 680+ I would say, but since the UK government imposed a strict quota for international applicants, competition for shortlisting is more intense so a higher UKCAT score would be safer. Aim for at least 700 or above or else stay away from UKCAT heavy unis. EACH UNIVERSITY HAS DIFFERENT SELECTION CRITERIA, MAKE SURE YOU VISIT ALL THE MEDICINE ADMISSION PAGES OF RESPECTIVE UK UNIVERSITIES BEFORE YOU COMMIT.

Work experience in hospitals and/or volunteering is almost compulsory for UK applicants here. Admission tutors want to see that you are really dedicated in pursuing the profession. It's probably harder in Malaysia to find hospital work experience, but volunteering in orphanages, old people's homes, hospices are equally as good. You will have to take the initiative to find these opportunities. It doesn't have to be hands on, it could just be cleaning/making tea/chatting to the residents there. Make sure you talk about your volunteering in your personal statement and reflect on the experience by writing what you learnt.