Grip leads probably be your best bet on beach and river, well it is in my area anyway. Never had any problems with them. Can make them yourself as we'll if you buy a kit and can save money.
Chris aka Dusty Bin is your man, lives in Horden: http://www.nesa.co.uk/forums/sale/190186-grip-leads-boat-leads.html
Where you's buying leads from - anyone recommend anyone local as would rather give them business than online somewhere.