Its on!!!
I worked out that instead of grinding away the rear cross member and weakening it i could just grind of the captive nuts from the bracket and push the new allen headed bolts down through the rear cross member and it slotted into place.
The only bit now is it sits slightly low and i cant get one of the 4 holding bolts on.
I'll adjust that in the morning.
Looks a lot better now.
This picture show the captive nuts gone and the allen bolts pushed down through instead of upwards.
This picture shows how i finished the fixing with nuts on the bottom.
This picture shows the grip tape in place and
this picture shows it sitting level.
The last nut will be in place tomorrow.
<phew>
For those that are interested its a Disco Parts heavy duty rear bumper.
:D