Where does one buy drain covers, of the 2'x18" sort that cover chambers where drains meet? I have such a thing in my patio which has rusted through and needs replacing. I'm not necessarily looking for absolute top best price (it's not like I need twenty of the things) but I assume I'd need to go a little further afield than the usual sheds.
Not done any drain stuff before; I assume that replacing a lid is as simple as it sounds, but any pointers welcome.
Cheers,
Pete