Hi
I would not use a Dry Powder in a small workshop for the following reasons:
You vision will disapear in an instant (may cause issues for you getting out)
has issues with respiratory issues if enough is inhaled
Will destroy any other electrical equipment in there (electrical systems) due to the way the extiguishant works
As already mentioned it is very messy.
Personally, I would go co2 and water, water for all the carbonaceous materials (wood, papaer, textiles etc) and co2 for the electrics. But to be honest if it is a fire in a wooden workshop, that are generally full of wood, chippings, sawdusts, oils, waxes, glues etc then the fire may start and spread at a very rapid rate so an extinguisher might be next to usless. All portable fire fighting extinguishers should be serviced every year and the user should check them on a regular basis especially if they have guages fitted to them, which may indicate a drop in stored pressure (large co2 canister inside it).. To be in with a chance then you should have a decent smoke detector fitted within the workshop in addition the the extinguisher/s.