Susan,
Yeah, my last trip to Similans was using Sea King Divers and their liveaboard called The Witch. It was affordable, the DMs were quite good, the rooms comfy enough (A/C throughout the day and nite), and great food!
If you havent dived for 2 years, I would strongly encourage you to do a refresher before going to Similans or a liveaboard. When i stopped diving for just one year, I was really rusty, and I really f***ed up my first dive after the long interval! I jumped in without regulator in mouth, dropped my mask in the deep, couldnt equalise properly on my second dive hurting my ears in the process, had major problems with my buoyancy, and kept knocking into everyone (basically annoying the hell outta everyone)
It took me at least 2-3 dives to feel comfortable in water again.
Similans/Surins is fantastic, but there are many sites which are challenging with strong currents. No doubt you will be taken to an easy and relaxing dive site for your first dive, but still it takes time to warm up and really feel comfortable, so why waste all those precious dives on "warming up?" The best thing is to do some day trips from Phuket as refresher - these are around 2,500 - 3,000 baht for 2 dives (some places will be more expensive). There are daily trips leaving for Anemone Reef, King Cruiser, Shark's Point and Racha Islands which all the dive shops conduct. Once you have done that, when u move on to Similans, you will be more relaxed and be able to enjoy Similans to the fullest!
Another possibility is doing your refresher in Korea - there are places where u can dive and should be cheaper than Phuket?
That's interesting - i thought diving (OW and AOW) were some of the modules which were offered as part of a marine biologist course.
Again, I would suggest that your husband gets Advanced certified before going on the liveaboard to Similans. My friends did their Advanced on the liveaboard, and throughout the 4 days, they spent more time studying than suntanning! Unbelievable! Why dont the two of u do the course together at Phuket? Then you will both be able to do night dives and deep dives together, and many of the nice sites at Similans will be rather deep.
Hope this helps, and do drop me a note once u have firmed up your travel plans. Have you also considered diving in Phi Phi?
Not as nice as Similans for sure, but great place for refresher and chill out.