>> I dont have much of wood work skills so might be lot of trial and error to make a good one.
you can learn a lot from trial and error
Other options are to use sleepers and dig a hole and make it at ground level.
(but you have to bend over then).
you can use cinder bricks & blocks - sometimes cheap on gumtree.
These don't need cementing if one or two blocks high.
And they can also b used to make a sturdy stand if your skills are not so good.
An easy option is to use galvanised fence post pipe for the frame.
These are strong and you can then get the various connectors that bolt to make the frame up.
Example is Doctor Fish -> viewtopic.php?f=18&t=28102&p=559034&hilit=doctor+fish+perth#p559034
Try a fencing supplier. Can sometimes get in rubbish dumps and salvage if you are prepare to clean up and angle grind.