The WHV insurance, Cap Working Holiday is a complete package of insurance and assistance benefits to cover the insured for the duration of his/her overseas trip, whatever the purpose: tourism, holiday, work, volunteer work, wwoofing, Couchsurfing, HelpX.
When you leave the European Economic Area for more than 90 days, you will no longer receive any benefit from the French social security or from your private health insurance. It is therefore essential you subscribe to an insurance to cover your medical expenses in case of an accident or illness.
Please be aware that medical expenses overseas can be very expensive and that a simple appendicitis can cost up to $20,000 in Australia. A medical repatriation to France can also cost a small fortune.
Also be aware that while overseas, the civil liability insurance included in your comprehensive home insurance policy will no longer work as soon as you leave your French residence for a long period.
It is fundamental to have an appropriate insurance policy to protect you in the most serious situations and not subject you (or your family who stayed in Europe) to very expensive payments.
This answer only relates to: Cap Working Holiday.