Hi @golfer50

Welcome to the Bunnings Workshop community. It's wonderful to have you join us, and thank you for sharing your question about what workbench to use.

Based on the conditions you've laid out, I recommend using the 2200 x 600 x 26mm Acacia Solid Oiled Hardwood Project Panel. I suggest pre-drilling the benchtops and using a cup head bolt and butterfly nut to keep the benchtops attached to the 2x4's while in use. Once you're done for the day, the bolt can be released and the workbench can be stored safely. 

The benchtop meets some of the conditions you've stated. It is sturdy enough for the worksite at 26mm and can take a bit of weight. It's light enough that you can still carry it to and from your vehicle without needing assistance. If cut in half and joined together to provide more depth, it will provide you with a working space of  1200mm x 1100mm. Which meets your size requirements. Please note that like all timber benchtops, I suggest sealing it with your choice of oil or varnish to protect it from moisture damage.

I've placed an image below on what it might look like, please tell me if you had another configuration in mind.

If you need further assistance, please let us know.

Eric