I'm doing my first TA cruise in April also.
However, I'm leaving out of Miami and ending in Italy. Per Yahoo weather in April the average low for Fort Lauderdale is 66 and the high is 82 with 3.91 inches of rainfall, in London, England the average low is 38 and the low is 54 with 2.10 inches of rain fall. London's high is lower then FT. Lauderdale's low
. My suggestion is to bring layers. Also I decided to bring convertable pants they convert to shorts. That way I only need one pair of pants. Here is a men's pair I found.