Hi,my vw bora tdi has awarning light on the dash board,it bleeps for about 5 seconds then a message on the dashboard reads ENGINE WORKSHOP!and glow plug light keeps flashing,brake lights are working ok.

SOURCE: Brake Lights 2003 VW TDI Golf not working???

This was a recall a couple of years ago, too.  I took it to the dealer and had it fixed for free.

SOURCE: i have a vw bora 1.9 tdi and the heater plug light

There are a number of different causes of this problem. Check all glow plugs. Check glow plug relay. If both are ok....This may seem unusual...Check the brake light switch situated at brake pedal. A faulty brake light switch will cause the glow plug light to flash
Good luck with it
John

Testimonial: "i have sorted this problem out now and your diagnosis was spot on i had three glow plugs out and the brake pedal switch was broken this fixed the prob"

SOURCE: MY GLOW PLUG LIGHT IS FLASHING IN MY DASH BOARD VW

Despite what you may read from other comments....The glow plug light is simple a multi function warning light and IS among many othed things in fact used to warn of brake light and brake light switch failure. Therefore it can NOT be treated as glow plug problems only.
I have worked on V.W for many years and have encountered this problem many times. You should get the OBD codes read. This will reveal the exact problem...and there may be more than one
You can contact your V,W agents if you wish and check to see if I am correct.
Best of luck
John