It isn't that hard
As somebody that runs a small business, it really isn't that had to make tax digital, I used to use a spreadsheet and moved to software. The cost of the software/time invested in doing it really does save so much time in the long run.
I use FreeAgent and it costs me £261/year ex vat, it automatically calculates
Self Assessment (with a few additional inputs)
VAT it calculates itself from the transactions you record, submitting is pressing a button and entering credentials.
It also does:
Day to day Accounting, with feeds from the Bank.
I spend probably 1 to 2 hours a month doing the accounts, things like Payroll unless changing staff details is just login and press submit, enter the HMRC credentials and away you go.