Autofil until the end of the column - vba

Question

My original program is able to find the Cells I need based on Month and Week now I need to modify the program to copy the last used cell in Row 5 and paste it until the end of the column.
Ex. If the month if November and it is the 4th week then the program knows to go there and fill in the information. I cannot figure out how to paste value from Nov wk 4 into the rest of the column. Also my range could be H5:BA5 or BC5:DB5 depending on where the month and week start.
I have added a picture that shows how my data is set up, the highlighted cells need to be filled in until the end
With ThisWorkbook.Sheets(SheetName)
Dim c2 As Integer
Dim LastCol2 As Integer
c2 = 2
LastCol2 = .Cells(4, .Columns.Count).End(xlToLeft).Column
Do Until .Cells(1, c2).Value = "Sept" And .Cells(4, c2).Value = "Wk 5"
If .Cells(1, c).Value = MonthSel And .Cells(4, c).Value = WkSel Then
.Cells(5, c2).Select
Selection.copy
ActiveCell.Offset(0, 1).Select
Selection.Paste
Application.CutCopyMode = False
Selection.AutoFill Destination:=Range("H5:BA5"), Type:=xlFillDefault
Range("H5:BA5").Select // need to change this range to reach the end of column 5
End If
Loop
End With

Answer 1

First off you need to STOP USING .SELECT!
Secondly, you already figured out how to find the last used column in your code. Why not use the same logic to find the last used row?
With ThisWorkbook.Sheets(SheetName)
Dim c2 As Long, LastCol2 As Long, LastRow As Long
c2 = 2
LastCol2 = .Cells(4, .Columns.Count).End(xlToLeft).Column
Do Until .Cells(1, c2).Value = "Sept" And .Cells(4, c2).Value = "Wk 5"
If .Cells(1, c).Value = MonthSel And .Cells(4, c).Value = WkSel Then
.Cells(5, c2).copy
.Cells(5, c2).Offset(0, 1).Paste
Application.CutCopyMode = False
LastRow = .Cells(.Rows.Count, 1).End(xlUp).Row
.Cells(5, c2).Offset(0, 1).AutoFill Destination:=Range("H5:BA" & LastRow), Type:=xlFillDefault
End If
Loop
End With

Answer 2

A much simpler solution (if we assume you have some sort of lookup formulas in your cells) is to grab all of column B and auto-fill all 52 weeks:
Sub TestingIt()
Dim LastRow As Long
With ThisWorkbook.Sheets(SheetName)
LastRow = .Cells(.Rows.Count, 1).End(xlUp).Row
Range("B5:B" & LastRow).AutoFill Destination:=Range("B5:BA" & LastRow), Type:=xlFillCopy
End With
End Sub