Hi Aidan,
I have done this twice (from weston) but on both occasions I was a student pilot, and my instructor handled most of the unusual stuff.
First time went to Isle of Mann. Stayed pretty low (about 2000ft from memory) to try and stay under controlled airspace. You will be asked for time to cross the flight information region, so have that worked out.
Second time went south along Irish coast, and then from Wexford to Wales. Again stayed at 2000ft. What I most remember most from this was the poor radio communication while half way accross. We had to use another aircraft ahead to relay messages. There are a few danger areas out to sea here. Watch out for them.
Also remember to bring your passport!!
Hopeing to go back to Isle of Mann this year now that I have my ppl.
DP