how to fix my transit 280 2.0td 2002 plate?

my transit cut out and wont start.has always started without hesitation until last couple of days but has only been slightly hesitent.driving yesterday and glowplug light flashed on,engine lost power and cut out within a few seconds.it now cranks over but wont start.the glow plug light has flashed up in the last couple of months whilst driving but never affected running or starting,and always cleared when turning ignition off then back on.any ideas of what i should check and in what order?