Book keeping type app/thing?

I wouldn’t want to keep records, does that income justify the cost of insurance and training/certification for the work? I’ve always balked at the hassle of getting paid for tree work, I do it as a favour or not at all. 

(Like so much else, doing stuff as a favour and not for profit means you’re covered under your own standard house insurance policy, doing it for profit means you need proper cover and that usually means you need certification. See also: giving someone a lift versus working as a taxi driver, though in this case it’s your car insurance that’s relevant.)

Brightbooks - web based, very simple but free and works well for simple bookwork.

I just write down my accounts as I go along, in the format required for self assessment.  Easy peasy, I just add up numbers on a train, coffee shop etc.  Used to hate it, 1 q enjoy it now.  

My small business is 40 years old in summer. I’ve always done things in the old fashioned way. Records have in and out goings. Invoice number, customer name, date and amounts. Type of payment. Also columns for car, equipment, phone and sundry outgoings. Just simple straight forward, something that’s easy to fill in and read back. I keep all records for 7/8 years (just in case you get a visit from the tax inspectors).