Should a resident of Jeddah, who then travels to Europe, enter into a state of Ihram for Umrah from his home in Jeddah, or from the Miqat upon his return to Jeddah? And what is the specified Miqat?

If you intend to perform 'Umrah upon your arrival, you must enter into the state of Ihram from the Miqat you pass through. Passing the Miqat without Ihram necessitates a blood sacrifice (dam). Some scholars hold the view that it is permissible for you to go to Jeddah and stay there without Ihram, then enter into Ihram for 'Umrah from your home in Jeddah whenever you wish.