I have an uncovered manhole in my garage (courtesy of the previous owners), it is an unusual size 660mm x 600mm and I'm struggling to source a cover for it. It's in an area that ideally I'd like to stand on often and I'm frightened of my 5 year old falling into it. Does anyone now if I can use a larger cover to cover it. As it is in my property I have been advised it is my responsibility to sort.