i have never heard much good about snap on diagnostics on the range rover, i much prefer the allcomms as it is specifically designed for it or faultmate.
i had a recent problem after my mot when the car had been left hanging on a ramp and i was getting HDC, ABS, HDC, EAS faults, even the HDC was cutting in as i started to move locking the wheels, i had so many bongs it sounded like big ben at midday in my car. i think the height sensors get crap in them when taken beyond their normal day to day travel. The connector on the transmission i have had issues with in the past which just needed reseating properly.
if you can borrow an allcomms i think it would help you.