Linking 'text' into formulas

I'm devising a employee rating system. Is there a way that I can link the text in Name Column to the other worksheets. For example if you look at my name it links across =SUM('Matthew Bailey'!$B$18) to the work sheet with my name on it.

It would be great if I have a formula that took the 'text' out of column and put it into the formula so if change the name it changes where it looks for the data.

So when I copy it down to the next line it looks into A5 which contains the text 'Steve Speller' then looks into the 'Steve Speller' Worksheet. The formula then becomes =sum('Steve Speller'!$B$18).

I am sure there is a very simple way of doing this but I can't seem to suss it.

Any help greatly appreciated.
Thanks,
Matthew