UK wouldn't touch it with a barge pole unless they thought you were going to pled guilty. I suspect the number of instrument approaches flown without a valid ticket is relatively high in the UK amongst the multicrew IR fraternity. If nothing happens nobody cares.
I know if the wx got a bit ****ty I wouldn't hesitate in going IMC if I thought it was the safer option. Not likely to happen though as if I am in a spam can I wouldn't be trying to fly in marginal wx these days. If its un-forecast there is not a lot they can do about it.
France you would be in the slammer and in front of the sheriff the next day. A wacking great fine would be imposed and you plane impounded until you pay it. And it would takes years and years of appeals and you more than likely wouldn't get the fine back and it would cost more than the fine anyway.