Have you checked to see if your model is part of the latest recall programme?
The WMXTF742GUK, KUK, PUK & PUK.M are all affected.
See here for details:
The recall is due to a wax motor in the door lock mechanism overheating and possibly, on rare occasions, causing fires.
Coincidentally, among other faults, a problem with the door lock mechanism may cause pauses in the machine cycle!
Or, if there is water in the drum when the machine pauses, there could be a blocked outlet hose/filter/sump, or faulty pump. Give them a clean out and see if that helps.
Are then any error codes on the machine?