A garden in the Languedoc will be a real challenge. I suggest you read the MGS Forum and join the local MGS branch.
There are several elements to a med garden: Firstly the technical elements which are well covered in O Filippi`s book.
Then there is the botanical or plant element. To-day there is a wide choice of plants suitable for a mediterranean garden (MG) and many sources of information . Take your time, look at what is successful in your area, discuss plant choice on the MGS Forum and with Branch members. Start a list of desirable plants and the characteristics that you like.You can still follow Jekyll and Lloyd colour shemes; it will take time and some effort to learn the new plant species.
The last element which is rarely mentioned is the mental approach to a MG. The difference between gardening in a mediterranean climate and a temperate (maritime) climate could not be more different. You can forget most of the practices and principles learnt in the UK. Start again with an open mind.
The med climate is dry, dry, dry and dry. Rain occcurs during autumn, winter and in the spring, for a few days and then it pours down. Take advantage and plant in the autumn when the soil is still warm. Planting at other times is not usually encouraged. Because it`s dry you have to be prepared to water in the first year at least. Your chosen plants should not need watering once they are established. A med garden is full of colour in the spring and again in the autumn. Be prepared for dormant plants in the middle of summer and again in the winter. These should not be boring however with appropriate use of shapes, seed heads, leaf colour. Forget many of the old favourites like hybrid T`s, hostas, geraniums, bedding plants, English lawns......its just too dry.
My wife had a real problem with a med garden, thinking that it was always necessary to irrigate. . This tends to be the rule with professional landscapers in the region. It may be that they wish to sell irrigation equipment
Grow some "exotic " vegetables such as squash, peppers, okra, toms, aubergines, Good luck.