I have a 2003 1.9TDI Octavia which has covered 166,000 miles

It is getting increasingly more difficult to select first and reverse gear. The bitting point of the clutch is about 1 inch off the floor.

Can the clutch master cylinder linkage be adjusted on the Octavia?

I guess this could be a faulty master / slave cylinder, or at worst the need for a new clutch?

What are the likely costs, as the car is only worth around £800 according to Glasses Guide, it might be time to cut my losses and PX for a new car

try bleeding the clutch first from the slave cylinder.