It is nice to find that you have a bit f British influence even though you are amidst US military personnel
.
100-200 orchids would NOT constitute a 'farm' . I have more than 175 orchids and the collection is barely noticeable.
If you are thinking about a few hundreds I'd suggest just keep adding a few at a time. May be try different varieties and see what suits your conditions and/or meets with your convenience. I assume you will have more interests now since you are retired and may need some time to pursue the others as well.. And you could stop when you reach an optimum number of plants to keep you fully occupied without them seeming to be a burden.
If they thrive well and if there is a demand for orchids in your area ( quite doubtful with only 150,000 pop.) you could sell a few for 'peanuts' . That will bring people to look at your collection too!
Beside it will be great to let school kids to come and take a tour of the farm.
Start with about 25-30 and build it up. It will be a great hobby.
Good luck and best wishes.