Always good to read everyones opinion on this as there is a certain ‘interpretation’ aspect to the tacho rules depending on different jobs. Me I go for balance I won’t show a break under 15 minutes (or 15 then a 30) and if I feel I have had to much break will use other work (POA at a push) even if I’m on a break.
Mental note + notepad and pen works for me, I record every moment of the day on it, mileage/tacho mode/arrival departure time etc.
I keep this notepad safe in case questioned by VOSA about a specific day, with little personal codes to remind me if its a proper break or I’m being a little naughty and might have to wing it. 