Two weeks to do oil. OFTEC 50 before you can go on to 101, 102, etc.
Only gives you the basics. Frightening really.
You're probably best finding some oily person to work with you on your first few jobs. Much more comfortable for you and much safer for the customer.
Nowdays there are a number of good, experience oil technicians who are not oftec registered anymore (mainly due to red tape and expense). If you can hook up with one of these you can learn loads then sign their work off for them.
Similarly, I knew of an oldish electrician (now retired) who was briliant at electrics but couldn't sign off work so he teamed up with a younger person, taught him enough to pass exams and this younger chap became registered then was able to sign off their work. When the older one retired he passed on all his customers to the (now not so young) chappie (who is now my sparky).