You've well and truly confused me with your point problem and it's effect on the UP and DOWN line Pete
On the West Coast Mainline in the "Makerfield" area the UP lines are the ones which head towards Warrington (and London) and obviously the DOWN lines are the ones going north towards Preston.
As I have already been reprimanded once by the forum Admin for editing another member's picture I have decided to live dangerously and have taken the liberty of superimposing the main signal (4-aspect) positions on a copy of your trackplan. I have also marked the normal running directions for each track but I didn't label them UP and DOWN because although I am assuming that "Makerfield" is south of Wigan I couldn't be sure from reading your thread which way the bay platform faces (north or south). In one of your photos you show some punks waiting to board the stopping service to Liverpool but I didn't know if that was the DMU at Platform 1 or another train that was about to arrive at Platform 2.
Although the plan shows (in my opinion) all the main signals that are needed you will also have to consider how you intend to operate the diesel depot. If locos are to leave the depot and then reverse back through Platform 2 this line will also need to become bi-directional. Movements to/from the diesel depot can be controlled by small subsidiary signals which might be something you could consider at a later date. Another possible problem is the positioning of the signals between the tracks......will you have enough space, allowing for rolling-stock overhang or will they need to be raised up on overhead gantries? Hope this helps.
Makerfield_signals01.JPG
P.S. I forgot to say. I spaced the signals on the assumption that the length of your longest train would be determined by the length of your storage sidings. If your plan is not to scale then you might need to reposition some of them.