Paving over a concrete base. - Rec's for paving over new concrete base

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Good Morning All,
I am (or the Chief fairy has ear'oled me into ) having a garden room built. The base of this 'room' is 100 mm of concrete over a MOT1 base blinded with sand with a 1:80 slope. The finish she wants is Bradstone Fossil Bluff.
What do I lay the flags on? There seems to be no definitive answer but rather opinions from sharp sand only to differing mixes of sharp sand and cement with/without SBR and the flags wetted with water/slurry/nowt etc.
What are the recommendations from the professionals on Paving Expert?

thanks

[seanandruby]

mortar with sbr.

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Thanks Sean