A definitive answer for that is all but impossible. Back then ships depended much more on the ocean currents. If the was blowing against the ship, it added more time. If the wind was blowing with the ship, the voyage would certainly take less time. There's also other issues such as storms, and those can really put a damper on the time. One of the worst issues, of course, is getting into battles at sea, which can tack on a lot of time IF it causes severe enough damage to the point where you must have your ship repaired at the nearest port. There's also the issue of food. Most meats and such would packed with large amounts of salt to preserve them. However, it only lasts so long, so if you run out of food, and especially fresh water, your ship is in trouble. You would have had to restock on food from time to time. Luckily, it's not as far as some places. Corsica is an island that east and slightly south of the Iberian peninsula (Spain). It is considered to be a region of France and has been a part of France since 1764 (almost 350 years). Anyway, estimating travel time was far from an exact science, and even with all of our technology today, you cannot estimate an exact time of arrival, because there are too many variables, although it would be a much shorter voyage today.
Now, for my comments about the chapter. I thought it was great. There was tension, love, and politics. Oh yes, it had everything we've come to expect from Mark. I see foreshadowing, however, of how poor Cavendish will take it when he is reassigned or whatever. He will take it really hard. He has many lessons to learn I'm sure. I'm also quite certain it's a good thing that George is on his voyage and away from London. This will give The Brotherhood as well as his wife and father to do what they can to give him more credibility, and hopefully by the time he returns, we'll find that Admiral Wilcox is a former admiral who has been forced out of the navy in shame.