Hello again emmatm,
Looking at the data for the line charts, one problem is that each of the lines has 5 data points (row 4:8), while your columns only have 4 data points (5:8). This is why you have the extra blank space.
Next, understand that the line only has a single point it's drawing to for each label on the x-axis. IF you only show 1 label on the x-axis, you just have a single point, and there won't be any visible line. Or, you can show all 4 of your labels, and the line will instead connect to the points, which will be centered over the label.
Your last question is the easiest to answer. Right-click on the chart, go to Select data. In bottom left is box for "Hidden and Empty Cells". Click that, and check the box in the dialogue that appears.
On a side note, I would suggest a chart design change. Currently, you've got the lines and columns are next to each other, but it seems more likely you'd want to compare the forecast to the actual, e.g. forecast of Agile Desks to Allocated Agile desks. Changing data layout to this:
Lets you make this chart:
Which IMO is easier to read. I can now see that we're good at forecasting offices, but greatly overestimated on Agile Desks.