I've written about impressment a couple of times here:
https://www.reddit.com/r/AskHistorians/comments/2oo91z/during_the_age_of_sail_how_reliable_were/
and
The short answer to your question is that no, impressed men did not receive any kind of "basic training" because "basic training" in the way we think of it in present-day militaries didn't exist in this era. If you were to enlist in the present-day Royal Navy, it would be for a term of service, you would be given standardized aptitude tests, undergo basic training in various shipboard tasks and duties, then go to a specialized school based on your preferences and the needs of the Navy, then be assigned ship or shore duty for your term of service. During that time, a bureaucratic institution would track your service, pay, aptitude results, health, assignments, and a welter of other details, and when your service term ran out you could choose ot reenlist or just walk away.
Service in the Navy during the Napoelonic period wasn't like that -- while commissioned and warrant officers had their service tracked by the Admiralty (for purposes of seniority/promotion), individual enlisted seamen were enlisted on individual ships for the duration of a voyage, and were rated according to their demonstrated nautical skills. Someone impressed on board a ship might have been an experienced sailor who was unlucky enough to have been pressed off a merchantman, or someone who was in town selling sheep and was unlucky enough to be the target of a press-gang. Either way, they would learn skills by doing, and the merest landsman would at least be useful to haul on ropes or lend strength to a task, but there was not a formal training regimen.