Let's not get carried away - what this means is that I've cut an 8' x 4' plywood sheet into four 1200mm x 600mm sheets. But hey, it's a start.
Some pictures to mark the momentous occasion:
Four neat matching boards. The job was made easier by getting a decent handsaw - I picked a cheap one up from Screwfix that cuts both ways. Less effort and less of a ragged edge to the uncut side.
Next up - bracing to support the plywood.