You could try a stone chip protection pack? Had one on my 06 polo GTi. VW quoted an hr to fit and it took them four, I did laugh!!
Worked quite well although it didn't cover the whole bonnet, just the leading edge, front bumper and mirror covers.
You're not going to stop them all. Having to have my windscreen replaced on my 30 due to the same plus an irritating wiper arc scratch on the drivers side although it happened to the previous owner and i want her mint again, not cheap from VW!
Ventureshield also do something similar but would budget for 300 pound upwards.