Many british charter airlines fly to orlando, but I suspect they sell tickets only for UK origination. You could try a consolidator like
http://www.yatratravel.com/index.php
AA has seasonal service MIA-MAN starting in the fall, not sure if that flight operates for your dates, but you can check on that (TPA-MIA has frequent service). AA would be considerably more comfortable seat than the charter airlines (more leg room).