@59CosG95 thanks for that comprehensive list!
I’d noticed the Standedge one and wondered what it was about. The ones further north/east make more sense.
No worries.
Between Staly & Standedge, there's a compound on the Down Hudds side to the north of Heyrod feeder, just before the line goes over the A635, complete with RRAP. Then comes Scout Tunnel, *those* houses at Mossley, and Mossley Stn. The Up Hudds cess north of Mossley station looks like it could take a compound (particularly near Portman St), but is so far untouched. There's another Down Hudds compound nr Grasscroft (just after the line crosses Oaklands Rd) before the line reaches Greenfield.
Finally, there's a small RRAP by Diggle Jn SB - I'm sure this'll be one of the big compounds when W2b kicks off.
East of Leeds, meanwhile, there's a RRAP off Marsh Lane (by the sectioning cabinet), shortly before the Richmond Hill cutting, which could feasibly hold a compound for E2. Neville Hill has a large space on the Up side at the depot's western throat (i.e. south of the railway) which could also work. Nothing obvious beyond NL to Cross Gates, but the gentler topography could lend itself to a number of possible temporary locations.
On to E3, and the proposed site for Thorpe Park (currently empty) could be a decent compound, as it has a level crossing.
East of the M1 overbridge, the line passes Barrowby Lane (aka Nanny Goat Lane) crossing (slated for closure), followed by Barrowby Foot crossing (also planned to be closed). The foot crossing off Dale Croft, west of Garforth, is AFAIK not planned to be closed.
Garforth has a compound in the car park and a RRAP east of the station (AFAIK that's for the AfA scheme there), and there's a vehicle-reachable access point by Woodlands Drive east of East Garforth; there is however no RRAP there. Finally, just shy of Micklefield, there's a RRAP off Phoenix Avenue. East of that is Peckfield LC (due for closure). "TheTRUpgrade" says that they're considering building a TSC on land south of the line near Micklefield too, and that a temporary compound to facilitate this will be required.
Finally - E4. Nothing after Micklefield until Laith Staid Lane, just past Huddleston Grange (due west of Sherburn-in-Elmet). Then another large gap until the 3 LCs due for closure as part of E4's works; Adamsons, Poulters & Rose Lane. I expect the existing compound at Church Fenton would likely be retained for E4 use after E1 is done.