I haven't gotten my results back yet but DNA tests go back as far as 50,000 years. I've done a lot of research on my family and 95% come from Britain directly, I do know one side of the family comes from France that moved to Britain over 1,000 years ago and 250 years ago, they came to the US. I'm guessing it will pin point that region. However, you have to remember, what this pinpoints is based on your DNA, not necessarily where your ancestors came from, meaning, your DNA markers will show where that DNA is mostly from around the world. It all depends on how far back the DNA looks. If your Haplogroup is G, in other words, most of your family could have lived in France for 1,000 years but your DNA markers show you came from Iran, for example, which is where it comes from. Your features may be different now because of the mothers DNA mixed in with it but Paternal DNA would show that is where your DNA originates, not necessarily where they lived. Your blood can't tell you if your grandpa lived in Britain or Spain, just where that mutation of bloord group started at. Again, it all goes back to how far they go back. If you take a DNA of yourself and your father, your Y DNA will match exactly. However, the further back you go it changes, which take you back to it's origin. Enough markers will link you to someone 300 years ago.
I would also mention, the R1B1A2 wouldn't separate you from Britain or France as that is the area this would come from. If you have that but all your family came from Australia for example, the test will say Britain/France as areas you most likely come from. I'm surprised it distinguishes France and Britain, to be honest. That's a tight pattern.