We use bactodetsan larder disinfectant . I think it is the stuff the "quality assured " people recommend . It comes in 5 litre tubs , is fairly strong (you just need a splash) and costs about £20 . You can get them from bushwear and various other places.
Try StarSan. It is used in restaurant kitchens etc. safe for human consumption. I got onto it when homebrew inn wine and beer. Never had a bad batch through contamination and you have to be super clean when brewing.