Many people set up their own bookkeeping system on Excel.
David Porthouse & Co have a free spreadsheet system to save you the trouble. In fact, if you use their system, they will give you a discount because when you send the spreadsheet back to them, it is in a standard format which is readable by computer. If you use the David Porthouse system, you are doing the work for your accountant and this is worth some recognition. Note that this spreadsheet can be used in tandem with an identical paper system, which is something to consider.
If you use your own spreadsheet system, then speaking from experience there is no efficiency gain to be hoped for, and you will end up paying twice for the same piece of work, once by your own effort and once in the form of the accountant’s fee.
If you really want to design your own spreadsheet system, then to add a column of numbers you should use the SUM function and overshoot the range at the top and bottom so there are no problems if you insert or append extra lines. If you do not do this, then you may find that the accountancy fee is actually higher compared to not keeping books at all because your accountant might have to detect and unravel what you have done as well as preparing accurate financial statements.