What to use for 20mm porcelain onto level block paved patio

[ashers26]

hi im putting 600 x 600 porcelain tiles down onto solid block paving. the paving was sealed 2 years ago with resiblock . there a few little dips here and there no more then 3 mm. i was advised to use mapei ADESILEX P4. with a 10mm notched trowel .
could some one please advise.
thanks
ian