Missmuffet

My skoda fabia estate tdi 2010 has a warning light flashing and I keep losing power until it come to a standstill. Handbook says its the glow plug warning light. Once I've stopped and turned off engine for a while, it starts ok but plays up again after a few miles. Anyone have any idea what the problem could be?and is it dangerous to carry on driving until I can get a machanic to sort it out? Thanks guys