This pattern brings back some lovely memories for me, as it's very similar to the cardigans my Gran knitted for me when I was a baby.
2 variants are included in this pattern - one has a hood.
For this project, the Baby DK range will be ideal. You'll need up to 4 balls depending on the size and style you are knitting - check the third picture for exact requirements, though remember that this pattern uses the 50g balls, so chop your number in half. Although King Cole yarns are recommended, you could also use West Yorkshire Spinners' Bo Peep range, which do come as 50g balls.
Photos courtesy King Cole.
Size: To fit chest of 41-66cm (16-26in), which corresponds to 0-7 years.