I'm not aware that Laurels can be overwatered but i'm not an expert on them.

Bare root trees and shrubs are going to take some time to build their root system and whilst they're doing it they definately are going to need plenty of water and if you too have had very little rain there then you should have had the hosepipe out once a week to keep them moist.
I'd start watering them and keep your fingers crossed.

By the way, what purpose does the mesh matting serve ?
The pebbles you're using as a mulch to reduce water evaporation, that i understand.
Can the water reach the roots through these barriers sufficiently ?

Have a look at this link. It shows a photograph from which you might be able to identify your hedge but whichever laurel it is, the planting and watering advice is good. http://www.roguevalleygardener.com/Landscaping-Articles/how-to-grow-english-laurels.html

A thousand bare root plants is a long hedge.
The preparation for multiple planting and/or hedge planting is crucial because it is so expensive if they fail.

So, for hedge planting, digging a trench would have been a suggestion and then placing the plants into this well prepared area and making sure that the watering / irrigation is done on a regular basis, to make sure the roots get off to a good start.

I'm still inclined to think that as you have had a dry season so far that the plants roots haven't had as much moisture as they could have done with and if you've been told that watering's not that good for them you might have hindered their growth a bit.

Unless you've planted your hedging into a concrete trough with no drainage, it isn't possible to over water them in open ground. Water, water, water, and you'll need to do that during dry spells for the first 18 months to 2 years, till they're well established, especially as you planted them bare root - right now, you're in danger of losing the lot without sufficient water in this very dry spell.