Dave - easy one to sort!
Buy from someone like GSF the gearlinkage bush kit, linkage rods (two rods with plastic cup end/clips) and fitting is a straight forward swap - even for a novice! It's just a case of taking off old and fitting new - just need to be a little double-jointed but it's not too bad.
Second stage if this doesn't completely sort the problem would be the relay lever (at bottom of gear lever is connected long rod, at end of this is like a metal square that has the relay lever in it - it's just a metal plate with a rubber ball on the end.) Think they're about ?13 from VW from memory. Finally, you can look to change lever bearing plate at bottom of gearchange lever. This is priciest option at about ?33 from VW so perhaps do the rest first?!
Overall, DONT buy the bits off eBay cos you'll get ripped off!!
Hope this helps Dave