Step 11: Join legs to top
You should do it a better way. Epoxy and steel dowels. It is what I originally had intended doing. Definitely no screws and no filler.
To mark out your dowel locations first set your top upside down and put the legs on it. Line them up where they are supposed to go and trace your pencil around the outline so that where the leg goes can be clearly seen on the top when you take away the leg. Then offset from the inside line by 12mm to get a line for your 10mm dowels. Mark their locations. If you have dowel markers you can use them now. If like me you haven't you just drive some panel pins into the locations to about half their length. Cut the tops off the panel pins. This should give you a nice sharp edge.
Get your leg and place it down on the top again so that the cut panel pins stick into the top edge and mark the dowel locations in it. Remove the nails and drill everything carefully with a 10mm bit. You just kinda have to eye it really. I must say the little bubble on my drill that I always thought was gimicky was pretty handy for this.
Clean out the holes and test fit. If everything is good then mix your epoxy and get it assembled. Clamp down the legs lightly so as to add some pressure but not enough to open up the joint. Epoxy the joint as well, or wood glue, whichever is handiest.