Glow Plug replacement

[Dr Steve]

Any help is appreciated with this one.

I have a 2003 Renault Megane 1.9 dCi and suspect one (or more) of the glow plugs needs replacing. The local dealer will happily charge £100+ to diagnose and fix the problem (they did last time), and am reluctant to pay that much as I can source the plugs locally for about £8 each.

My question is, how easy is this job? And where do I start looking for the plugs? I understand they can be a bit tricky to get to, and a long reach socket will be required.

Cheers.