i was gonna say, parts dept wont be open on a sunday, sales munkeys only ;p
though im sure they will try to book you in for a £65 inspection anyway
when you do get the correct lower front crossmember dont forget to slap a few good coatings of hamerite on it before you fit it, as its gonna get hammered by all the crud on the winter roads.
the ABS main unit is fitted to the NearSide inner wing within the engine bay under the battery tray.
nearside brake valve ?????
i'd give all the Near Side pipework around the ABS UNIT and caliper a good visual inspection, make sure all pipework is secured to all the clips (check for corrosion, if any then slap hamerite all over it after giving it a rub down).
Have someone press the brakes with the wheel off and engine running so you can see what the NSF brake hose is doing, any bulging etc.
i honestly dont know what else you can do other than ring/go round the mot station and ask them to litterlly! show you what they are on about.