Hi! Based on my testing and experience with these models, here are a few thoughts regarding your setup:

Regarding the driveway, if it is loose gravel, the caster wheel on the Yuka will likely dig in and get stuck. However, if it is a solid stone driveway (like slabs or cobbles), it should be perfectly fine. For reference, my driveway is block paving and the mower works with no issues at all.

If your path is loose gravel, rather than spending the extra £700 for the AWD Luba, you could simply make a small adjustment to the path the mower follows. Laying down a narrow strip of pavers, stepping stones, or a solid track through the gravel for the mower to transition on would solve the "digging in" issue for a fraction of the cost.

Since you mentioned having lots of trees, having the LiDAR working in tandem with the camera is a really good option. This dual-vision system is much better at navigating areas where the tree canopy might interfere with a pure GPS/RTK signal.

If you can make that small path adjustment, the Yuka should handle your 600m2 garden and transitions between lawns perfectly well!