Visit England’s Channel Islands cruise

You could fly with Aurigny airlines.

They aren’t actually in England, or the UK.

The Channel Islands are the last part of the Duchy of Normandy in the hands of the British monarch - they conquered us, we didn't conquer them!

I visited Jersey with my family some years ago (it's the largest of the islands) and found the most interesting part the remnants of the WW2 defenses and other structures, notably the underground hospital built by slave labour. I don't know what the local bus services are like but we hired a small car (you wouldn't want a big one on Jersey's roads). Frankly, I didn't find it interesting enough to want to go there again.

There are flights from Southampton, or ferries from Portsmouth or Poole - these also call in France (St Malo).
A bit more information about your hopes/plans would help is give you more information,
The Channel Islands are not part of the United Kingdom. They are British Crown Dependencies, which means they are self-governing possessions of the British Crown but are politically separate from the UK.

The problem with a cruise is that the harbours are small, so generally cruise ships can't dock- they have to anchor off, with tenders ashore, if the water is not too rough.

Guernsey has a greater than 50% failure rate for cruise calls.

Sark, Herm and Alderney all lack the infrastructure to handle even small cruise ships.

So as a general rule a cruise is not the best of ideas to visit the Channel Islands, although of course you can always have good luck and beat the statistics.

Either fly or catch a ferry.

Both Guernsey and Jersey have excellent bus services.