IT Contracting in France, best way to start?

Hi Valerie, I will try to explain my situation in one long description, I hope you will be to grasp it and help me with your advice.

I am Croatian citizen (EU member- full rights of movement for France) and yesterday I have moved to France/Toulouse to start working for one big international company as IT freelancer/contractor providing them my professional intellectual services.

As the whole story was done by UK recruiting company and I was given random French accountant from Paris who unfortunately not helping me at all as his service is bad. The only thing I was told that he will register me as self-employed in France and did not tell me any details which flavor of self-employment, how much TAX and social security I need to pay etc, which brings me to your forum…

Here are some facts that I would like to share so I hope they can help you define my best status in France for upcoming period:

• My assignment in 2017 is only 2 months and its probe period in which I would like to define my status for 2018 to be clear how much I will be earning netto if I decide to prolong my stay in France. Later it will be 6+6+6+6 Months rolling contract.
• If I sign for 2018 my gross/brutto contract is equaling 560 euro/ day, average month cca 11500e and full year cca 120 000 - 135 000euro gross (depends on vacation but just to get a picture of TAX table where I fit)
• I will be spending in France not less then 6 months in 2018 (erliest that I will leave is 01.7.2018 ) and not longer then 24 Months in total , most work time I will be here in France cca 80%. most probably I will spend 12-18 Moths here .
• I am 37y old, married with one kid, having property in Croatia, wife and kid will stay in Croatia and live and work there.
• I do have self-employed status in Croatia as well and can provide myself A1 certficate for 2018 so I was think about posting option as well   but did not know that until last week and in meantime, my accountant started registration for French self-employed status. Can I shift between does two statuses easily?
• I will have fixed business expenses of cca 1500e per month for flat and airplane tickets ( how much I can claim actually per month 10-15% or more? And can I claim expenses as a posted worker using A1 certificate?
• How much would be my net take home cca projection , can I have a least 60% nett of this gross 120-130k per year? Can it be better with A1 status? I have not found any TAX or Social tables for Self-employed, can you help me with this caclulation at least rugh numbers?

As you see I am trying to figure out best status for me in the upcoming period, thing is that if I can get only 50% retention hardly that I will be staying in France at all I hope it’s not so bad I am open for all potential solutions but I dont speak word of French so I asume some things like setting up own company in France would be quite complex… I hope you will be able to summarize it for me.

Waiting for your answer…

Thanks and If you need aditional info let me know!
BR
Ivan