Thanks for the advice & kind words :)
Last night I decided that it just wasn't worth losing sleep over, so I practiced something different. Went back this morning with a clear head, feeling relaxed & pretty much nailed it on the 2nd take :)
On the subject of pressing the button, I record my solos using auto punch, wind the recorder back 3 bars before & hit record, that way I've got time to step back, get a proper grip on the pick & count myself in for 4 or 8 beats, so I don't feel rushed.