A parallel working system is a paper system with an identical spreadsheet system which could be used in tandem.
One such system is produced by David Porthouse & Co. There are a couple of ways to use it:
Learn the paper system, and then the spreadsheet system.
The paper system has cash at the left and bank transactions at the right. It is intended to help you work out how much cash you have left in the kitty at the end of each week. The bank page is intended to be a straight copy of the bank statement, but with anonymous cheque payments being replaced by the names of real payees. Once you have learnt the paper system, you can switch to the identical spreadsheet system and e-mail it back to David Porthouse & Co. This is a sensible route into bookkeeping.
Use the paper system during the week, and write it up on the spreadsheet system later.
If you have plenty of cash receipts, write them down at once on the paper system so you have a permanent record. At the end of a week, month or quarter, transfer them to the spreadsheet system and use the calculations on that system to check the kitty total. Here the paper system can be called the Day Book, and the spreadsheet system can be called the Ledger, but they look the same as each other. You might find this an effective way of working.
The spreadsheet that you e-mail back to David Porthouse & Co will be read electronically into their main accounts preparation system. You will get a discount for this because you are doing some useful work in advance.