Electrification - It very much depends on the scale of other work required first (and deciding what is needed) as this is an upgrade programme not just electrification. Hence areas where the least other work (including option selection) is required first will probably get electrified first.
Diversion options (including Northern service and freight) are also a key part of phasing.
Vic - Stalybridge & Colton - Church Fenton fit the bill for being done first.
Indeed. The majority of Miles Platting - Ashton-u-Lyne - Stalybridge could feasibly be done in a single blockade, or spread over several weekends, with TPE routed via Guide Bridge. Bustitution between Ashton & Stalybridge, with ticket acceptance on Metrolink to Vic might be an option for Northern pax. Calder Valley diverts for TPE when the work reaches Stalybridge itself and/or the Philips Park Triangle; for such a short distance, infilling between Guide Bridge and Stalybridge would be an easy win too IMHO.
Miles Platting Junction itself will be the big "Alan B'Stard" of the work; this would probably involve diversion of TPE services via Guide Bridge, and termination in Man Picc.
Meanwhile, Colton - Church Fenton has the distinct advantage of being 4-track, so it's reasonable to assume that, on
open route stretches of track (or
plain line in p-way lingo) services could be concentrated on 1 pair of tracks at a time at weekends, and could vary between either track depending on location. Of course, at S&C locations, mid-point anchors, and termination anchors, full possessions would be needed for boom installation, as portals (rather than TTCs) would inevitably be required.