I'm glad to hear that it has worked out for you! I'm living just outside of Rennes in Brittany with a single mum and two kids of 6 and 12. Although, I never speak English to anyone, the kids don't seem to want to learn either. Aw well, suppose it helps my French. With regards to the travel insurance, I don't actually have any other than the EHIC. Within a week of your arrival in France, by law, you should have signed a contract stating that you were becoming an au pair which then has to be validated by the local social security office. There is an example contract on au pair world that you could use and there should be a clause in it that in the event that you become unwell, the host family will look after you and continue to provide you with accommodation and food until you are better.
This was taken off the website:
"To ensure that the placement of your au pair will officially be recognized in France, you need to sign the au pair contract, officially called "accord de placement" (agreement on placement), together with your au pair and add necessary supporting documents. You need to have it validated by the competent areal unit of the DIRECCTE (body in charge of companies, competence, consumption, employment and work, former supervisory board of work on departmental level) close to your home. The set of documents needs to be validated before your au pair leaves his/her home country or one week upon arrival at your home at the latest. The contract defines your rights and obligations, as well as those of your au pair.
In France, au pairs are covered by health, maternity and accident insurance (for accidents at work) throughout their entire stay as an au pair.
To enable them to benefit from the insurance, you need to register your au pair at your local URSSAF (Unions de Recouvrement des cotisations de Sécurité Sociale et d'Allocations Familiales) as "stagiaire aide familial étranger". The registration should follow within 8 days upon his/her arrival at your home. At registration, you need to ask for a form which you will take along to insure your au pair at the social security (Sécurité Sociale). You also need to obtain the au pair's social security number, which is necessary in case of illness.
Afterwards, you will receive a nominative declaration (déclaration nominative simplifiée (DNS)) from the URSSAF every three months. It will help you calculate the contributions you need to pay on a monthly basis. You only need to pay employers' contributions and these are not deductable for tax purposes.
Although I really don't know how much of this applies to you considering you are not really an au pair, although you could be classed as one?
Any other advice, I'm not really too sure! Moving here was really hard for me, but I have to admit the most difficult thing was the lack of social life to begin with. Although, I have found people now and I'm enjoying myself a lot more!
If you have any questions at all or even want to chat feel free to PM me.