Apparatus and method for milling a hole in casing

Wellbore operations (e.g. for milling and/or drilling) are disclosed which require a reduced number of tool trips into a wellbore to create a cut-out pocket or window in a tubular such as casing in the wellbore and, in some aspects, to continue into a formation adjacent a main wellbore forming a lateral wellbore in communication with the main wellbore. Preferably one trip is required. A milling apparatus has been invented with milling apparatus for milling a tubular member and a nose cone releasably connected to the milling apparatus and releasably connectible to a diverter that directs the milling apparatus toward the tubular member. A nose cone for a milling apparatus has been invented with a body member, the body member having a mid portion, a top portion and a lower nose portion, and the top portion releasably securable to the milling apparatus and the lower nose portion releasably securable to a concave of a whipstock. A whipstock has been invented with a body member having an upwardly extending concave portion with a concave surface, and at least a portion of the concave surface contactable by a milling apparatus during a milling procedure covered with armor material.