Some responses from elsewhere:
How long is the ride for ? You can use your UK license for 3 month I think,may be 6 or 9.
There's nothing to stop anyone taking their riders test as far as I recall, certainly driving a car wasn't one of the criteria. Passing the test but then, getting a license, may be where bit goes fuzzy. I know I bought my bike in Atlanta on a UK license, insured it on a UK license and then rode it across the States. I only took my car and bike tests when I had finished crossing the country and bought a car here in Seattle some months later.
Get an International driving license from the UK post office before you set off.Confuses the hellout of the plod over here!
First I'll state the obvious. There is no national driver's license in the United States. Each state sets the criteria for a driver's license.
Generally, a person has a driver's license for operating a car. Then they get a motorcycle endorsement on that driver's license. I guess it is possible to get a driver's license without having driven a car. But, I never heard of it. I some states, passing the MSF course qualifies as passing the riding part of the motorcycle endorsement test. You still have to pass the written test, if any.
Your UK driver's license, with motorcycle endorsement, should suffice for 90 days or so. If you stay longer, it is wise to get a state, in this case Florida, license with motorcycle endorsement. An international driver's is valid but I don't know if that covers a motorcycle endorsement. Since the local and state police rarely if ever see an international license, they will look at it with great interest.
Getting a driver's license and motorcycle endorsement is a extremely easy here in the US.
In central Florida, try Orlando Harley Davidson. They offer MSF courses. Nice people and they have a permanent dedicated riding range and classrooms. Great instructors are often FHP motor cops. A free days Harley rental is sometimes included with course fees. I presume only if you pass.
Can't say about the endorsement, but maybe they can give their take on it. See if this link works.
BTW I have an International Driver's license with a bike endorsement.
All the best