Rugby concrete path mix as a shed base? - Shed base using dry concrete mix

[CalamityJane]

Going back to a previous note; I think I should support the back of the shed (the 7' that's going to go along the length of an unstable fence) with a concrete block.

I could make a wooden frame (shuttering?) to fit into the ground about 8" deep, 12" across and 7 foot long. I plan to leave the frame there and follow previous advice on bulking it with metal (although I don't have an old bicycle).

What mixture of sand, cement and pebbles should I use to fill the frame please? and should this be done in one go or in layers?

Thanks

[lutonlagerlout]

4:2:1 pebbles;sand;cement
much better to ring one of the many concrete companies in london and get them to deliver 1 m2 and then you just barrow it in and level it,cost you about £100 for 1 m2 on its own
hope this helps ya
LLL