The crash pad is held down by 10 nuts. You have to get at them from under the dash. The studs from the crash pad go through the metal dash frame, and the nuts hold it down from underneath.
You're going to want to do both the fascia and the crash pad together. The Leyland manual advises you to remove the fascia first (starting with the centre panel), then disconnect the air flow control from the fascia. Remove the 4 nuts holding down the demister vents and remove the demister vents, then remove the other 6 nuts securing the crash pad to the body. Pull out the ashtray bowl, unbend the tabs holding the ashtray frame and remove it. Then carefully raise the crash pad to free the studs from the body, lift out the crash pad.
I found getting the fascia out (and disconnecting all the guages, speedo, etc) was by far the more difficult part. Once that's done, crash pad removal is pretty straightforward. They do tend to stick in pretty tight, but just put gentle, contant pressure on it to free it up and it should come out ok. The metal base of the crash pad itself is pretty thin, and if you yank on it too hard in one spot you could bend it, which could make it a real pain to get the dash contour back.
I have not installed the crash pad overlay.