I am a little late to the party but hopefully not to late to help or even if I am this may help other business owners who are leaving the country as I had to go through this process and am now totally free to run my businesses wherever I am in the world as long as I have an internet connection.
I currently live in Saudi Arabia but my limited company and businesses are in the UK (set up before I moved). Most companies for contract hire to require you to have a UK limited company for their payroll purposes, so it is not surprising that they want you to do this. Although this may seem complicated and will involve extra work (in handing in accounts and end of year statements, set up costs extra) you will also see the financial benefit of running a limited company rather than being an employee, which should level things out for you, ie you can claim legitimate expenses related to your work, your set up, accounting and address costs will also go down as business expenses. Plus you will be free to also engage in other contracts should you want to.
Setting up a limited company is reasonably cheap (generally under £100). However this does mean that you will need to submit your payroll monthly and your accounts and annual statement yearly. I would suggest you hire an accountant to handle this for you (the cost of which is also an expense for accounting purposes). The only thing you need to report is your salary (that you pay yourself through paye) to the French government, the company tax and expenses will only need to be reported to the UK government, which is what your accountant should handle (I would suggest using a UK accountant). You will also need to fill in a
P85 to tell the government you are leaving the UK.
Having a business address is easy. I use
www.ukpostbox.com for this, they receive all of my mail under my business and personal name and scan it for me to see and download. This actually makes accounting a lot easier as it is already digitalised for me and I actually wish I had used them when I ran the business in the UK. It also gives me a premium business address so it doesn't look like a post box either, they will also forward mail, shred mail and even take cheques to the bank. I have been using them for nearly a year now and they have been a perfect solution for my needs. They are also very cheap considering the hassle they save and the service they provide and I have not found the service lacking in any way.
Now working virtually will demand that communication is clear, so a good telephone line is essential. I use a fellow UK business forum member who was recommended on here in a post I placed looking for a solution. These are
www.voipfone.co.uk. They offer a UK based phone number (multiple ones as well so you can have one for personal and one for business) over voip (you plug the phone into your modem, REALLY easy to set up especially if you buy their phones and it is just like using a normal phone, you can also use it on your mobile and tablet if it is connected to the internet or forward your calls at the touch of a button). Their service has been outstanding, the phone line is as clear as if I was in the UK and I am in the middle of the desert!! Calls into the UK are cheaper than chips and calls from the UK are no different than if your caller was calling any landline in the UK. Your extension and phone number rental rates are really cheap as well, it really isn't a considered purchase as it would cost you more to phone the UK anyway. The biggest cost is buying the actual handset, however I have two walk about phones that are better and were cheaper than my previous BT phones and it came pre programmed with my account data on it. You don't have to use their phones but I would highly recommend doing so. Again I wish I had used them in the UK too, certainly more effective and cheaper than it was to have my two BT lines.
That is it, that is all I had to do to make the jump to a business model that holds no limits in terms of location. I can sit in the sun and successfully and efficiently run my UK businesses. Don't let the process put you off, it is worth it and having this system in place helps manage your personal affairs to in the expat lifestyle. If I can do it in the middle of the desert, you will have no problems doing it in France. Good luck and Bon Voyage!!