Hi clairec1976
What a great surprise that this will be for your husband.
7 days is not a lot of time. I think that you may be looking for the romance of a Thai beach and missing the best of Thailand.
Bangkok is the normal 'Port of entry' to Thailand so, unless Thomson offer direct charter flights, ther is no way that you can justify travelling to Phuket, returning to Bangkok on an overnight trip, and then going back to Phuket. You also mention some of the attractions, but in my view miss the major one - the Grand palace which is not to be missed.
Fiona has made a couple of very good points - especially that 7 nights in LoS will take up 8 days.
She also suggests a different itinery and different Tour Operators.
First advice
If you haven't been to Thailand before and you are not familiar with the Far East do not try DIY (you may also find that flight costs through a 'package' are cheaper!).
Second advice:
Day 1 - Arrive Bangkok, anticipate a short stroll round to familiarise yourself, go to bed and get over the flight. (Try the Landmark, near the skytrain on Sukhumvit - easy to travel around, good hotel, unbelievable price)
Day 2. Go to the Grand palace - not to be missed (you can do this yourself -
http://www.stickmanbangkok.com/travel.html#tour.
Day 3. Go to the floating market (yes it is a bit touristy but also a not to be missed item). The Rose Garden is a bit iffy but you do get to see elephants and Thai dancing.
On one of these days (Day 2 would be best) - especially if it is your husband's birthday, try
http://www.manohracruises.com/d_dinner.php for dinner
Day 4 - end of holiday. Transfer by road (< 3 hrs) to Hua Hin, either the Anantara or Hyatt which are next to the beach and in beautigul 'garden' settings. You will find that you will probably get a Thai dance show at your hotel.
I can thoroughly recommend the poolside Thai restaurant and Thai dancing at the Anantara (e-mail them to find which night of the week has the dancing). Although I have never tried elephants trekking in Hua Hin, I'm sure that it can be found. (yes my wife and I love the Anantara)
Recommendation
My recommendation would be Premier holidays, using EVA Air flights (upgrade to elite class is you can afford it - Premium economy ) or Thai airways flights, 3 nights in BKK, last 4 in Hua Hin. Note also that Premier provide private transfers to all destinations (airport to hotel to Hua-Hin to airport) included in their prices.
Suggestion Both Thai and EVA leave Heathrow about 9:30 pm - could you leave 'late' in the day after work and add that extra precious day.......
The beaches are not as nice a Phuket, but I think that your husband and yourself will get more of a 'real' and interesting Thai experience.
Others may perhaps disagree
Weather
http://www.wunderground.com/global/stations/48475.html at the end of November last year it was mid 80s and some cloud but quite good (you can check the history from this link).
Whatever you decide - enjoy your trip.
Good luck
Peter