foundation raft above ground level.the sides of that raft are rendered and this keeps blowing off.Can i hack off render,seal concrete sides and put natural stone all around?

I would get a professional to come and test the damp levels on the property and seek some expert advice, rising damp can be a major worry in buildings. If all is well you could natural stone around it!

If the house is on a raft , this is normaly underground ! by about 2 course of bricks , plus 2 course to the DPC . This is for frost protection . Could be that the ground has sunk away to expose the raft , which has then been rendered . A landscaping feature wall, say .450 wide , could cover it up and provide a bit of sideways frost protection. Peter.