I would recommend coachbolts from either Screwfix or Toolstation. Better range of sizes from Toolstation. Cheaper than the ones advertised as screwpegs but appear exactly the same. Bought some 8mm diameter ones from Toolstation last summer as replacements for my bent and damaged ones, no noticeable difference in quality. Also got some 10mm penny washers and some 10mm wing nuts, stick the washers on then the wing nuts on upside down and that will do in place of the plastic hooks/tops on the ready made ones.