Over dry bricks might not be such a problem as there will suction. Putting it on rend-aid at 10-12mm in 2 passes wet on wet is going to make it on the heavy side. Tearing under it's own weight at the bottom and the dreaded rapid drying? Two equal thickness coats shouldn't be too bad say 8mm base set and then a 7mm top.
I will ring Encon? in Leeds and get some prices on Paramurex. What is the rend-aid equivalent in Parex language?