Best Mortar Mix for Engineering Brick Patio?

I have done this kind of job before on a slightly bigger scale, I would use a 150mm concrete bed, 6 shovels of sand and gravel and 1 cement or the equivelant of a C20 concrete mix, leave till semi dry, lay solid engineer bricks to suit your pattern leaving a minimum of 10mm between each brick, then allow to completely dry. The quickest and most successful way of sealing/grouting, I would say, is a two pack resin slump mix which is guaranteed against cracking and weed growth. Very simple to use, an area that size would take approximately 30 minutes from start to finish. Hope this has been helpful any more questions don't hestitate to ask.