From Appendix 9 to Part-FCL
FLIGHT TEST TOLERANCES
Height
Generally +100 feet
Starting a go-around at decision height - +50 feet/-0 feet
Minimum descent height/ altitude - +50 feet/-0 feet
Tracking
Angular deviation - Half scale deflection, azimuth and glide path
3D linear vertical deviation - -75 feet below the vertical profile at any time and not more than +75 feet above the vertical profile at or below 1000 feet above aerodrome level