The only point to remember is the weight and balance issue of four adults in a Warrior and the fuel load that it leaves. In the context of a long VFR flight accross water to France or the Channel Islands, the diversion you might have to make in the event of finding fog or mist on the other side is one back to the S/E of england.....
I flew from egtb to Caernarfon the other day, straight over Snowdonia and the scenery was unbelievable.
Good luck, it sounds like a fun trip.