Poplulate Userform TxtBox and still be able to edit the Txtbox

[BillLogue]

I have a Userform that has 2 radio buttons. Depending on the selection updates the worksheet automaticlly. It also has a textbox that I need to be updated with the cell that the radio buttons are linked to. That much I have completed. My problem now is that I need to be able to edit the text box so that when I press submit it updates a seperate cell. However once it is updated it can not be edited.

So that you know, the radio buttons are meant to load a template to the text box that needs to be edited based on the situation.

Here is the code that I have so fare

 Private Sub OffBase_Click()
    If OffBase.Value = True Then
        Range("TA!A43").Value = Range("TA!A41")
    Else
        Range("TA!A43").Value = Range(" ")
    End If
End Sub
Private Sub OnBase_Click()
    If OnBase.Value = True Then
        Range("TA!A43").Value = Range("TA!A40")
    Else
        Range("TA!A43").Value = Range(" ")
    End If
End Sub
Private Sub OnReport_Change()
    OnReport.Value = Range("TA!A43")
End Sub

Thank you in advance.