Hello mate
If you need a sand and cement finish, then as you have proposed is the traditional route to go down....
If you want a modern alternative, that will give a stronger and less likely to crack route, have a look at the link in my signature below....
If you want more assistance or advise, drop me a message on here.... (my work contact details are in my profile - click on my profile name top left and then view profile), but I am on holiday sunning myself this week.... lol
Good Luck
Richard Lord
Knauf Aquapanel Exterior Technical Manager