where did you have this done?
I used to have real wood dash kit by the same brand (B&I) on my 1999 Defender. And I did the installation by myself, nothing that complicated. It took me around 5 hours to install about 30 pieces.
You just have to clean all teh plastic pannels from dirt, grease, dust, etc. Then you will have to pre-fit the pieces before sticking them on. If everything fits okay, go and stick it. In my case, one piece did not fit the right way (it was cut wrong), so I had to wait for the replacement of that piece. The rest worked out great for me.