Best screed mix for porch floor

[pilgrim]

Hi all, 

I am finally back on my building project after a long distraction. I am building the porch at the moment and I am now unsure what mix to use for the floor. I think I have read too many websites different opinions. It will be a basic un heated porch. 2.2 x 1.9m internal floor area. To build up the floor level there will be 120mm insulation and then I was thinking 80mm of screed on top.

I will be mixing and laying the screed myself!

 

Originally I had thought of doing a biscuit screed at 8:1 cement to sharp sand. But a lot of other websites seem to recommend 4:1 normal floor mix. So I am now a bit unsure what mix is best

 

Does anyone have any good advice or experience that would help me out? 

 

Thanks

 

[Mr Punter]

Our guy used 4:1 with some fibres chucked in.  Get the levels around the edge then fill in the middle.