I am looking at the weather charts and it seems that it's not such a great idea to visit the Trang islands in the first two weeks of November, after all. They seem to be so perfect for laid back vacation, with snorkeling, no crowds.... Being stuck, can you, please, advise 1/alternative or 2/if you think that it's still worth going, let me know.
The question how to get there from Trang remains.
1. I wouldn't change your plans if I were you. I've been to the Trang islands several times in early November. Usually the weather is perfectly OK ... maybe one or two heavy downpours (usually in the evenings) but otherwise lots and lots of sunshine. One year the monsoon ended very late and we did have about 3 days of persistent rain but that's pretty unusual.
2. How to get there.
Perhaps the simplest way is to get the overnight sleeper train from Bangkok to Trang.
There are a number of cafe/travel agencies near the train station in Trang who can arrange onward transport to the islands for you. Just as you come out of the station there's a place called Seabreeze which I've always found to be very helpful but there are other places nearby too.
They'll be able to fix you up with transport to the island of your choice and also book you a room in a GH if you want ... they usually have pictures of all the resorts so you can see what they're like.
I'd advise you to book just one night through the agency in Trang. That way you won't be locked in. You'll be able to find somewhere else to stay by yourself once you're on the island if you don't like the first place for some reason.
If you plan to island hop then your resort will be able to arrange onward transport for you.
You'll see, it's VERY easy! ;-)
Yeah, early November is still normally wet season, but conditions are often starting to taper off, meaning more sunshine/less rain. And seeing full-on wet season is usually okay for Andaman travel, that can't be bad.
However statistically and anecdotally the wet season seems to end earlier in the EASTERN Gulf - check TRAVELFISH'S interractive weather map and stats from Thai Meteorology Dept
and - http://www.tmd.go.th/en/province_stat.php?StationNumber=48478
Note Samet, big Chang and Muk don't have great snorkelling off the beach - but Ko Whai is pretty good.
Also check their RAINY SEASON FORECAST - the table near the foot of this page:
shows they think the Eastern Gulf (CALLED EAST on the table) will have its NORMAL rainfall Nov this year -
BUT the Andaman will have BELOW NORMAL rainfall. Might have something to do with the local version of the LA NINA/EL NINO effect.
One place normally to avoid in early November is the southern Gulf - Samui Phangan and Tao which can get real wet. I notice the table is saying that area could be BELOW NORMAL. But below normal of REAL WET could still be pretty wet. Maybe not, I got one great November in that area. Ko Tao has pretty good snorkelling.
I haven't been to any of the Trang islands for a couple of years but Ko Ngai, Ko Muk and Ko Kradan are within easy reach of each other so you could spend some time on all of them if you want. Between them they should fit your wish list of activities.
You could also do an overnight camping trip to Ko Rok National Park if you want (probably most easily arranged from Ngai or Muk). The snorkelling there is the best in the immediate area though there is/was some OK snorkelling off Ngai and Kradan too.
Ngai used to be breath-takingly beautiful but a lot of new (upmarket) resorts have been built there since I visited... I don't know how that has affected things. Kradan is the least developed of the three and also has stunning beaches. Muk has canoeing and the Emerald cave, a village and more opportunity for walking but the snorkelling isn't as good as the other two off the main beach.
Travelfish has descriptions of all three in the "islands" section at the top of the page.