Mark, as with your other questions, the answer depends on the details.
1. How will you be registering the boat at the time you purchase it?
2. What are your plans for the boat when returning to the UK?
In general, the run from Miami to e.g. England's South Coast is not more difficult (nor very different) than stopping off in the various Atlantic Is. along the way but it is much longer in duration. This not only means provisioning is more challenging but that you also face the increased prospect that it may be necessary to call in somewhere along the way (boat system failure, illness, events back home which reach you via SSB, etc.). The basic run will probably be similar to the island-hopping run except you'll stay further N as you bypass the Azores. Keep in mind that this entire routing - USA's lower East Coast to UK - is best determined on a day-by-day basis with a careful eye on the sweeping LP cells that cross the N Atlantic and dictate all the major weather systems you'll see along your route. That's why many boats these days partly ignore the stuff you read in the guide books (e.g. Anne Hammick's Atlantic Crossing Guide - "go to 38-40N, then turn E") and instead use a daily routing service like Herb Hilgenberg's free 'Southbound II' service and also put aboard some means for collecting daily wx f'cast data, whether that's wx fax graphics & text f'casts, GRIB files, or other info (SSB or SatCom system). And BTW, if most of what I just wrote sounds a bit foreign to you, this is an area that would be useful to study up on a bit before leaving.
P.S. We never use Herb's service, which is outstanding since he's the Guru of Atlantic Weather, without sending him a small, unsolicited contribution to help support his large and impressive radio station. You will find his daily wx briefs to be highly valuable and the daily check-ins will begin to feel like neighborhood get-togethers among the participating boats. We always send the small contribution before leaving; that way he recognizes us and we get a little 'extra' TLC.