Sorry, the answer is none.
You used to be able to do this with most meters but there was a safety regulation brought in to prevent this about 6 years ago . ( apparently some people inadvertently switched and acted on the 'wrong' numbers)
I live in France but have become quite happy to use either unit and in fact one of my main meters is from the UK in mmol/l, the 'spare' from France in m g/dl . I use computer software ( onetouch software) that will change the unit. This means that the records I give to a doctor are in mg/dl.
It can really confuse doctors here if you inadvertently give them a figure in mmol/l since they actually use g/l (so 5 mmol/l (UK) = 90mg/dl (on mg/dl meter) would be written in France as 0.9g/l )
If you buy a meter in the UK; you will have to check that the same meter and strips are available in France. This isn't always the case. The adjustment for unit is in the meter, not the strip so strips bought in France/UK are interchangeable
as long as they fit that meter .(ie my one Touch ultra strips work in both the UK and the French bought meters)
If you have to buy a meter they are very much cheaper in the UK than in France.
http://medical.twenga.fr/lecteur-de-glycemie.html
If you are entitled to be prescribed strips in France, you can get a prescription for a new meter every 4 years. The manufacturer has to guarantee them for that period .
if you want to google to check availability of strips/meters in France the best place is the manufacturers French website. There are a few comparison sites but they all seem to be very out of date.