The way I see it is that the AME checks your health and then sends his findings to the appropriate aviation administration. It's the aviation administration who makes the decision whether you're fit to fly (based on these findings) and then issues you the medical.
So I'm only suggesting that it might just legally be possible for a French AME to fill in the appropriate British forms, send the whole lot to the UK CAA, who then issues you the JAR-FCL class 2 medical. Or, for that matter, fills in the appropriate Dutch forms, send the whole lot to the Dutch CAA (called the IVW actually), who then issues you the JAR-FCL class 2 medical.
But to be honest here... My medical is a Dutch JAR-FCL one, and I am by no means an expert on French aviation law when it comes to medicals. Maybe there is a rule somewhere that your medical has to be issued by your country of residence, or that aviation authorities only accept examination results from AMEs in their own country. Or something else making this scheme impossible.