AutoCad :: Plotting Emailed Drawing At A3

I have received a measured survey drawing from a survey that I wish to print out on A3.

The drawing and the title block are both in Model Space. When I measure the structural opening of a door, I found that the dimensions are in meters. On the title block, the denoted scale is 1:100.

I am simply trying to replicate this in paper space in order to print out this plan on A3 paper at 1:100. By the time I have worked through Page Set up Manager and chosen the scale of 1:100, the floor plan inside its border looks like a postage stamp.

I have tried Format > Units and changing the drawing units from unitless to meters but this doesn't change anything. I have also tried scaling the model space drawing x1000 but this makes the drawing too big in paper space at 1:100.