stewart killick
It depends on the size of the openings and the state of the brickwork etc but to insert a lintel you would normally insert acro props around 150mm above where your putting the lintel to support the weight of the wall above then you can remove window followed by the brickwork you are replacing with a lintel. Most competent builders would be able to do this. Personally I think it’s outside the scope of a diy’er but others may disagree
