Hi rhodyma
try this

Sub h()
If ActiveCell.Offset(0, -1) "" Then
ActiveCell.FormulaR1C1 = "=CONCATENATE(RC[-2],RC[-1])"
Range("E4").AutoFill Destination:=Range("E4:E6")
Range("E7").Select
Else
Exit Sub
End If
End Sub

if activecell = Range("E4") then cange it to
Range("E4") .Offset(0, -1) "" Then
Range("E4").FormulaR1C1 = "=CONCATENATE(RC[-2],RC[-1])"

Regards Yngve