Concrete Mix for foundations

[LeanTwo]

I'm constructing a lean-to extension that will cover about 13.5 square meters to my existing kitchen/diner.  The total length of the foundation, allowing for a 100 mm shoulder, is about 9.5 meters.  I'm looking at about 2.75 cubic meters of concrete. (9.5 X 0.65 X 0.25m)

 

I looked up a concrete mix on the internet and the suggestion was:

 

1 part cement

2 parts sharp sand

4 parts gravel.

 

Does this sound right?  I had other ratios result from my search as well!  My builder's merchant also sells a mix of sand and gravel.  This sounds like an easier option than separate deliveries of sand and gravel?  I hope to mix and lay this in one day, with two of us working.  Does this sound achievable?

[Vijay]

Ballast would be easier but I don't know how it compares price wise to getting the parts individually. I personally would get ballast if I was mixing myself