OP. did you book a hotel or an airbnb? If you booked via a booking platform then you may need to contact the hotel and ask them. Recently there has been a clapdown on unregistered airbnb etc selling daily and weekly rooms, which is illegal. they can only do 30 days or more (and still need to be registered)
For your short trip could you not just come on the 30 day entry. or is it that immigration HAVE to use the visa in the passport? Hopefully some group experts know.
Its been a long time since I got a visa. But you are better of getting a one year non B un UK from one of the Thai consulates. To open a business is another relevant mine field, concerning work permits, number of employees and company structure etc.