Dude,
ISE has more or less said it all. The Channel islands are fantastic, cheap and very accessible. I've given up going north on trips, I just head for the coast every time.
Remember that the crossing is only 2 or 3 time the Le Touquet distance and no-one worries about that. The only other safety feature I would recommend is another engine.(Less inconvenient than immersion suits).
As for the water temperature it is about 10 degrees all year round so the time of year should not affect your decision.
Weather the the CIs is always iffy, even in summer. I plan to get to Alderney 6 times this year and made it only once. Their waather is usually 40 kts in fog.
If you want a copilot to do your first trip with I would be happy to go.