Suppose I live in France and trade as money manager for a person from the UK, where do I need to be licensed ?
You need to be licensed and regulated in both the UK (FSA) and France. Maybe in New York as well if you're trading NYSE (FINRA) listed stocks.
don't forget about the 'great' taxes in France... why not move to a low tax jurisdiction? set-up in Gibraltar etc...
Based on what you say this ? Have been in the money management business ? Even when you trade in an unregulated market like forex ?