Might be buying My First Transporter (TM) tonight....! Very excited.

It has a 1.6, 4-speed Golf diesel engine in it - no more info than that. Took it for a little spin yesterday and seemed OK.
I know absolutely nothing nabout engines, and just wanted to check to make sure I'm not making a huuuge mistake: any tips and advice about what to look out for in such an engine?
Many thanks.