Filling values from the column on left or right

[VKS]

Hello Friends,
This novice user of VBA is back with another problem. Being a fairly good user of excel I work on huge pivot table called Master File created from a very huge access table.
I use this pivot table to cut paste info for various reports. Every time I cut and paste something my table looks like the sample shown below.
I find spending a lot of time in writing a formula in excel which is =IF(A2=””,B1,A2) then I copy and paste it till the last line of data (sometimes in thousands of rows) this works fine for me but since I use this more often so I decided to write a small macro for myself as shown below

 Sub FillColumnFromLeft()
'
' FillColumnFromLeft Macro
' Filling blanks of left column in a new column
'
  Do Until Selection.Offset(-1, 1).Value = ""
    ActiveCell.FormulaR1C1 = "=IF(RC[-1]="""",R[-1]C,RC[-1])"
    ActiveCell.Offset(1, 0).Range("A1").Select
    Loop
End Sub

And this didn’t fill even a single cell for me forget about going down 2500 rows.
I wonder if some expert can correct my formula above and guide me to understand coz after this I would want to write a code for picking up values from right column and do it till end.
Regards/VKS
Months Sales Person Item Sales area A Sales area B Sales area C
Jan Jack a 1 5 2
Jill a 2 3 1
Bill a 0(0 is Blank in data) 9 6
Tom a 5 1 1
Sam a 1 2 1
Feb Jack a 1 5 2
Jill a 2 3 1
Bill a 0(Blank in data) 9 6
Tom a 5 1 1
Sam a 1 2 1