Unless you can get at least some 10-15 hours out of your trip, I wouldn't bother - you will come back to UK, start with new instructor, new plane, new circuit/aerodrome/airspace procedures, you will essentially be back to square one and those few hours you got in US will not matter much. Now of course any flying you can get will work in your favor one way or another, but I'm afraid the value for money will not be there...
as for doing multiple lessons a day - I guess I'm a total wimp, I never took more than one lesson a day, I found it a bit too much even when I was doing a lesson a day few days in a row - I had to combine training with full time job and my head was wrecked after 3rd or 4th day. There's lot's to take away from each lesson, you need your cool down time, you need to do some reading and prepare yourself for the next lesson. The thing is - most people can learn to fly around the circuit in two or three days if they have to, but you're not just preparing for solo circuit - you have to see the bigger picture - you have to develop reflexes and habits that someday will save you from big trouble and you can only develop these properties if you take you take time between lessons