Just make sure you're supporting the crank arm when you go at it with the hammer -- this will help avoid transferring the force to the bottom bracket, which can cause some damage.

If I may, I'd suggest spending more time looking at those videos by RJ the Bike Guy -- I learned a lot from his concise, good quality videos, and I managed to do every bit of work on my recent (and first) restoration myself. Just as one of the great headaches is removing crank cotters (probably the hardest thing you'll tackle on this bike), one of the great joys is learning how much there is to learn about each component. Take your time. There is a lot of great information on these forums, too, which you can search using google. (Don't use this site's search function -- you'll often be disappointed.) And if it isn't obvious by now, we like to help, and we like to answer questions. Most of the regular posters on this site have decades more experience than I do...