Denise,
All the pitches have borders of bushes and/or trees, most of the pitches have at least a degree of shade although there are what appears to be newer pitches towards the rear of the site where the trees and bushes have still to reach a size where they will provide some shade.
Staff in reception all appeared to speak good English so if you were booking direct with the site you should have no communication problems.
On the two occasions I went I booked through Select Sites. I would recommend them, good service and fair prices.I go normally late June early July so its not that busy at that time. First year we went it was March of same year when we booked. The potential problem of booking via an agency is that they have limited numbers of pitches and popular sites like L'Garangoire can be in demand. The agents allocation can be full while the site still has vacancies.
I would suggest you compare prices of booking direct with site and ferry via web and with someone like Select Sites.
http://www.select-site.com/
Robert