For 0.1s and 63A fuse I see 720A mentioned (Fig 3A3(b) in BBB) so I2t = 720 * 720 * 0.1 = 51,84063 amp BS88 fuse and 2875A fault current?
A quick glance suggests we're down the bottom of the graph well before that fault current, so bunging 0.1 disconnection time in gives 18 sq mm steel needed. But I'm not taking responsibility for it!
Using Table 54.4 and assuming steel armour on 70C PVC cable k=51 so:
s = sqrt(51,840) / 51 = 4.5 mm of steel needed so well within safe margins as my Prysmain sheet lists 16mm 2C as 42mm of steel.
To get 0.08 Zdb at the end of the cable is impressive, it must be quite short (16m max even for Ze close to zero) or already have parallel earth paths!