Assistant Nursing Jobs in UK or Mental Health care worker?

I am a Registered Nurse in my country Nigeria before moving to UK to further my studies. I am new here in London and i do not know how to go about getting a part time jobs on Nursing Aide OR Nursing Assistant OR Mental Health Care OR Social Health care worker. A friend of mine said i have to go through an Adaptational Training in any hospital in UK before i can work as an Assistant Nurse or Nursing Aide here but i do not know if thats permitted for me as a foreign student. Please i need your candid advice here soonest.Do i need to go through any kind of training? and if Yes, which organization should i contact? I am confused and need help. Thanks a lot and God bless you all.