A new wellbore apparatus has been invented which, in certain aspects, has anchor apparatus for anchoring the wellbore apparatus in a bore, the anchor apparatus actuated by fluid under pressure supplied thereto, and sealing apparatus selectively inflatable to close off the bore to fluid flow therethrough, and temperature compensating apparatus for maintaining a desired fluid pressure in the sealing apparatus to prevent it from bursting or deflating. A method for closing off a bore in a well has been invented which, in certain aspects, includes installing wellbore apparatus in the bore, the wellbore apparatus comprising anchor apparatus for anchoring the wellbore apparatus in a bore, the anchor apparatus actuated by fluid under pressure supplied thereto, and sealing apparatus interconnected with the anchor apparatus and selectively inflatable with fluid under pressure to close off the bore to fluid flow therethrough, and the wellbore apparatus upon anchoring in the bore and inflation of the sealing apparatus including a primary barrier in the bore.