Don't worry about using other world seeds for anything right now. You don't need it. You have ALL the resources you need at this point to get through the game. See how you go. Obviously if you hate the grind or the idea of mobs flattening your home base build, use multiple seeds to traverse the Valheim "universe".

If you want to use another world for building or resources, think of it as just another address in the same world. 1A is your boss game where you do all your fighting, exploring, etc. 1B is your home/resource address. You can fill your pockets in 1B and log into 1A to transport things if needed.