Reckon Peter has it about right.
There is no reason why you shouldn't be doing it (ignore those who tell you that you need 1,000 hrs before you do anything meaningful with an aeroplane), but at the same time it's never a good idea to push the boundaries of what is legal and possible too much.
A PA28 Archer (180) would be a good shout. They can take a fair amount of weight and a decent amount of fuel at the same time.
However, the weight and balance situation is really, really simple. Do the full calculations for any aircraft you consider using for this trip. Decide how much fuel you need (no reason why you need to carry enough for the return trip, you can top up at Le Touquet) and then make conservative assumptions about how much everyone weighs. Then tell the ladies that handbags have to stay in the car, but add 20-30lb for general junk/coats/etc to the calculations anyway. Do the maths. You can either go or you can't. Make your rules about how much fuel you need before you do the maths - don't decide to make it fit the W&B.
I don't wouldn't fancy my chances if I was in the back of a C172 and the engine quit over water. Not only do they tend to flip, but can you imagine trying to get out of the back in a hurry - possibly with the people in the front incapacitated? At least in a PA28 you can climb over the seats if you have to.
It really is just a methodical process. Do the W&B and make sure it can be done with sufficient fuel. Then if that works out, make sure you're happy with the paperwork that needs to be done to fly abroad. It isn't too complex, but you do need to be absolutely clear you understand what needs to be done. As someone pointed out, file both flight plans the night before to make things easier. Then assuming we're still on, it's basically down the the weather. If you've done your PPL, then you'll know what is good enough and what isn't. To be honest, if it isn't good enough on the day then the authorising instructor probably won't let you go - but you should arrive at that decision yourself before you even try to sign the aircraft out.
No reason at all why you shouldn't plan this. But a lot of things will have to go right for you to get as far as backtracking to use every last yard, then lining up with 25 degrees of flap and putting full power against the brakes.
Last edited by niceday2700classic; 15th May 2012 at 15:33.