That's correct. You can't book US bound flights ex UK in the USA. For the actual holiday accomodation and internal travel you could use " Vacations To Go" . I have used them to book Caribbean cruises and then found my own way to USA. They are efficient, know what they're talking about and don't rip you off like the UK plus you have the added bonus of paying in US$ which at an exchange rate of around $1.90/�1 at the moment is a bonus. What they can do is get cheap fares from Canada to US for you so try flying Zoom Airlines or Transat to Toronto and then they do the rest.