A park with bbq facilities as they often have tables to spread out on.

The park and nature reserves

Guide and Scout hall and other community groups buildings often will hire out venues very cheaply

Nearby parks might be good.But it will be hard to find this kind of places due to covid 19 restrictions.

Depending a bit on the craft, parks are always a safe bet. On weekends, school ovals might be an option too.

Parks and Recreational areas are probably your best bet.

Another option might be to make diy craft kits and find an outdoor venue and also have a picnic.

Perhaps just a park of some kind? With a shaded area with chairs

There are quite a few websites such as Kidspot which have lists of free or cheap programs etc for kids during school holidays. A bit of a google search might help?

It might be somewhat tricky with rules and restrictions around covid-19? Might be worth finding some pages on social network sites that provide lists of possible venues and activities. Maybe also check with local what’s on activities and information.

Where are you located ? Museums and art galleries often have a venue for kids to do craft, you could also inquire by your local library about what’s on or search for activities in your local news paper.