igarratt
This is worth a look as the official source:
Jersey Met Dept Index. The Weather Professionals.
You should be in no doubt that the conditions for VFR flying can be fine over land and the forecast in the CI can be fine but over the channel you will have little or no horizon and the sea will merge into the sky. You can find yourself very close to instrument flying if not actually on instruments. The higher you go the more of a problem this can be unless you get on top of the usual summer inversion - but of course you need to find your way down again. Never mind about gliding to land in the event of the worst, in these conditions you are often better as low as you feel comfortable where the sea will give some perspective.
I have no intention of putting you off, just be aware that the crossing can be pure VFR or it can be a great deal more hazy than you imagine. A good tip in either direction is if you start to feel really uncomfortable surprise yourself and by turning back sooner than later the land behind will again give you the visual references you are comfortable with.
A final thought. The CIs weather is also susceptible to rapid change, particularly the onset of sea fog. I have watched on many occasions Alderney go from CAVOK to worrying about RVR in 10 minutes. Usually the forecast is reliable, but not always. Watch out if the forecast includes a cold front moving up the channel.