Just an update, I started laying more last night and I found a way that's working for me.
Which is just buttering the back of the tile and the floor with the 10mm notch. 90% of the tiles I put down so far sat down nicely first time 🙂
I got to say my body is aching today, I've been doing my house up for 8 months and I've done the plumbing, electrics, carpentry and plastering etc. but the tiling really wears on yours knees and different core muscles lol.
When I've completed l'll post a picture up so you guys can have a laugh 🙂