Hi Jimbo,
I have done two transatlantics, one on QE2 and one on QM2 - the latter was slightly more casual than QE2, but on my QM2 transatlantic, it was 4 formal nights out of six - tuxedo or lounge suit. I can't remember dress codes for the other two nights, possibly informal - jacket and tie for men, or casual - open neck shirts and slacks for men.
Shorts are pretty much a no-no in the evenings, but during the day, dress is very much what the weather dictates. I agree that the publicity photographs show people dressed to the nines, but dress codes are fairly relaxed. I'm sure you'll not feel out of place. I love the formal evenings and dressing up, but the rest of the time it certainly doesn't feel stuffy.
On QM2, there is the Todd English restaurant which charges, when I last looked, $20 per person for lunch and $30 for dinner. In the evenings, Kings Court (the self service restaurant) is divided into four themed areas, and one at least charges extra. During the day, there is certainly no charge and for meals elsewhere, there is also no charge. The Queens Grill and Princess Grill restaurants are obviously only available to those that book grill-class suites.
I'm sure you'll have a good time. Let us know when you get back.
Paul