Get signed up and get the ATPL theory out of the way if you can while hour building to 150hrs and remember to fit in your multi rating as well at some point.
Cabair still have there slave labour cadetships open until i think 35.
But using my scottish tightness i reckon its actually cheaper to pay for it yourself than take the cadetship if you are in a half decent job ie 20k+ a year. You have to work for three years for next to nothing and all the self financed F/O's will be on better money from the outset for the first couple of years. I don't know if the time spent on the cadetships will count towards your seniority either.
MJ