jamestkirk,
Love the name. As captain of a Starship you should know all this....BUT, as far as I can ascertain, you MUST make a position report in U.K. Airspace.....
(a) After transfer of communication.
(b) On reaching the limit of ATC clearance.
(c) When instructed by ATC.
U.K. IAIP ENR 1.1-12 has other conditions too.
Keep a sharp lookout.....