The RN may be able to conduct night carrier strikes, but in April 1942 they only had a handful of swordfish on their 3 carriers so probably would be able to hit more than a couple of ships, and not necessarily the big carriers. I doubt they could survive the counter-strike that Nagumo could launch in the morning. Sommervilles best chance to actually do something would be to attack where there are no IJN carriers, or perhaps join Fletcher in the Coral Sea.
Search Google Groups for "Battle of Addu Atoll".
The Swordfish had radar. They could attack the Japanese carriers by night. As Sir James put it, "Swordfish pilots are like whores, they come out and play at night."