I haven't flown to Orlando with Britannia for at least 10 years but I have flown with them to the Caribbean to join cruises. I'm afraid their long haul aircraft don't have seat back screens, the planes are extremely cramped, and I'm definitely not a fan of theirs.
However, that's flying from Gatwick, if you're lucky things MAY be different from Birmingham. The other thing I dislike is the fact that most of the charter airlines fly into Sanford, for us flying straight to MCO is a must. others like Sanford so don't be too put off by my comments - I'm sure you'll be fine - just think of it as a means to an end.