Longing for a saloon

First post here and hoping someone can give me some advice. Recently my 54 Reg Passat Trendline 100 has had the emissions workshop message appear. It's not 100% of the time but it's more often than not. Should I be calling the bank manager for an extension to the overdraft? I've taken a quick look around the forums here and see that some people have VAGCOM software and can hook this up with the right kind of cable. As I will be keeping the car for the next 3-4 years, would this be money well spent and has anyone an idea of costs?

First post here on what seems to be an invaluable forum site. My 2004 passat estate has recently started showing "Emissions Workshop" message on startup. It doesn't happen 100% of the time, but it's more often than not. I've read a few threads that suggest it could be various sensors. What's the best advice? Should I be taking in to VW? I've read about VAGCOM. Is this something that I can purchaes and if so will it save me £££ in the long run as I intend keeping this car for a few years.