You can do it by changing options in excel: first, go to office button, Options, Advanced--> Editing options, then , at the first option: After pressing enter , move selection to: and choose Direction: right from list (default is down)
Select the needed ranges, (A1-A7, then B1-B7, then A10-A17, then B10-B17, and so on), go to Home tab, Format-Format cells-Protection and make sure that Locked is unchecked. On the review tab, click on protect sheet, then ok (you can set a password if you want). Now, only those unlocked cells can be edited, and the selection will move to right when pressing enter.
The inconvenient in your case, is that you have to return to previous row after completing the first part of current row.