What money saving DIY prep can I do before builders arrive to remove a chimney breast?

[Isabeller]

It's in a basement so will have a hefty beam. There's an old (cast iron?) fireplace behind hardboard and a built in cupboard in one alcove so I'm planning to remove these at least. Is there any point in getting the plaster off the chimney breast myself?

The structural engineer also said the floor in the room above needs looking at. I think it's to see if there is the remains of a hearthstone. Could I do this?

If I want to help with labouring ie lugging rubble, will I need a mask? any recommendations?

Any advice gratefully received