Thanks doug
Ive used cloudcompare to open the laz file and sav as a txt file.
The txt file produced was 34 MB, which seems pretty handleable for my month old macbook pro.
However, sketchup fails to import it correctly. It says there is a failure, and then only imports a few randomly spaced points that dont resemble the original file view in cloudcompare.
Ive then folllowed your advice to thin out the spacing between the points. Ive thinned it to the optimum amount that just offers the amount of detail i need. This made the file size 5.4 MB but it still fails to import correctly, showing the same sporadic points as before.
Do you have any advice??
Many thanks!