To be perfectly honest it depends on your ability and on how much money/time you are prepared to invest in post PPL training. . .I'm told that at one time Lufthansa cadets had to solo on a Bonanza within 11 hours or get chopped. To be fair they had been through a selection process and so should have been talented (If the selection process worked that is). . .It is quite a big step to go from 90kt trainer to 150kt cruiser. Things will happen a lot faster and checking the met becomes even more of a serious business. Obvioulsy the IMC isn't valid in France so you'll need VFR conditions there. . .It is also worth thinking carefully about the speed that you actually need. No aircraft ever seems to go fast enough on a long trip, but you may find, depending on the length of the legs that an extra 25 knots doesn't deliver that much of an advantage in airborne time (125kts will take about 20 minutes longer than 150 kts on a 200 mile leg).. .Personally I think I would have struggled with that kind of speed and aeroplane just after my PPL.