Gite business structure?

We are an English couple.  My partner lives in the UK and I live in France with my mother, helping her run her gite rental business.
(5 gites, turnover is approx €60,000, running costs are approx).

My mother is a propriétaire of an old cider farm and she is currently registered as a travailleur independent loueur meuble professionel with RCS.

My mother wishes to retire, and my partner and I would like to run the activity between us.

His plan is to move to France.  This is unlikely to be possible before 31 Dec 2020 (Brexit deadline).  My partner is employed in the UK but may have the option to continue that work remotely from France for a limited period of time when he moves.

We need advice as to the best structure that works for us both given regard to healthcare, pensions, the legal side, minimising corporate and personal tax. 

Another factor to bear in mind is that the gites currently belong to my mother.  She doesn’t want to operate them anymore, she sees renting them to us to operate as a possible income source for her.
This is fine, but we need to consider inheritance as part of the big picture.  She has a UK will, and has dictated that her will will be executed under UK law - I am named as the sole beneficiary to her will.

We are aware of options such as conjoint, micro-entrepreneur, SARL, SAS but don’t really understand which are appropriate for our needs.

Where do we start?

thankyou!