Just put your toe in. You need to find turnip seeds, grow them, replant to reseed for a few cycles to get a decent supply and then upgrade your cauldron so that you can access the better foods that you will need in the swamp. While you are doing that you can hunt trolls to get fully upgraded troll armor, hunt or breed boars for boar meat since boar meat in required for better swamp foods.

Once that's done just explore the edges of the swamp because you will need dragur and leech drops to succeed. Take the time to stock up on things before doing a full recon trip into a large swamp to find iron.