Presume you mean FL45 not FL450. Or that's one impressive Mooney!
Sensible to fly at the appropriate altitude/FL per the semi-circular rule, though not mandatory for VFR. FL65 or 85 would be my choice for the water crossing from the SE (once past that annoying airway south of the IOW).
If you are talking to London Info, they will likely ask you for an eta to the CI zone boundary, so be ready for that (if using GPS, suggest you put a waypoint on the boundary to make this easier)