If you are brave enough to cut this by hand you will need to mark up the upper face of a 1220mmx2440mm sheet using the downloaded drawing.
The design is fairly tolerant of inaccuracy in the jigsaw cutting but you will need to cut the slotted holes in the lid to provide a tolerant holes for the tabs on the leg frames.
If you are using 12mm ply you will need to glue and clamp the pairs of table tops and legs to eachother. PVA glue will do the trick. You should clamp the leg frames on their tabs and about 10cm from the end of each leg. The table top needs clamping over the slotted holes.
If you want to add additional rigidity the table top can be screwed through to the edge ply of the leg frames. Use the lotted holes as a guide for where the legs are beneath and drill a small diameter locating hole through from above before countersinking a posi-head woodscrew.
If you like this table you might like other things I do....