You are broadly correct about exempted fencing – generally 1.2m to the front and 2m to the rear (Schedule 2, Class 5 of the P&D Regs).
I’m not aware of any Regulation of hedging – but, unless the hedge is between your window and the south to southwest sun, it is unlikely to seriously affect your light (at 2m).
I don’t think the Planning Authority will get involved – have you tried talking to your neighbour?