To do a little research in to all the requirements in CAA world Lasors is a good read!
I'll give you ahead start on this occasion.
Lets work backwards!
To teach PPL students you'll need a Flight instructor qualification(FIC),
To get an FIC you'll need a commercial pilots licence,
To
start a CPL you'll need 150hrs of which 100 must be Pilot in command,
To do hour building you need to have a PPL,
Most FTO's around the world are struggling to keep hold of good instructors. Most are jumping ship to fly the jets...
Expect good salaries and good working conditions coming to an FTO near you soon!!!