Clutch master failed. Two options available sensor or no sensor?

Hi clutch master cylinder I assume has failed. Can see fluid on and around under tray near master plus reservoir was low enough to let air into clutch. Ordered new sachs one as I cant do without car and don't have time to strip it down to get part number but on re checking there seems to be two. One with sensor and another without. Am I correct in thinking the one with sensor is for vehicles with cruise control as mine has. Got the part number from LLL parts 1k0721388ab/ac/af (its been superceded quite a bit) Any help welcome plus wish it was the slave but at least cars at home and its sunny. Its a 12 plate 1.6tdi estate 5 speed manual. Wish they had a clutch fluid low warning as well as low brake fluid

Alasdair