Don't make a meal of a workshop.
This is meant literally. It’s genuinely best not to bring along a substantial lunchtime spread to a workshop. Not a workshop as in a factory, or some place you do your DIY (knock yourself out picnicking in those places). But a workshop as in a meeting of "professionals" discussing business things like selling products at trade fairs – fully equipped with a PowerPoint presentation and the kind of people who take stuff seriously. Then it’s not advised.
Why? The simple reason being that they’re usually quite quiet, particularly when the main speaker is talking. And, if it’s a small one, there’s no way to be discreet while buttering your bread and blowing your hot soup furiously to cool it down. So save yourself the embarrassment of being the only one tucking in by waiting until afterwards to gorge. If you are starving and absolutely must eat, then bring something subtle like mini scotch eggs or some cocktail sausages. Don’t offer them round though.