The charities have a lot of information on their websites, below is some general advice to help you get those needles clicking.
The charities involved usually have free knitting patterns and advice on their websites so do not be worried by all the details as you really will be able to find a garment to suit both your knitting skills and the babies needs
Bliss: One of the many ways that you can support Bliss is by knitting for babies in special care units. Knitted items are most helpful for babies about to go home, but there is also a need for blankets and hats for babies in hospital. Knitted items are often not suitable for intensive care units – stitched cotton is preferable. However for larger babies, and in high dependency and special care units, knitted items are often very welcome.
Bonnie Babies mainly makes blankets for premature babies. They provide patterns for toys, hats, and sweaters (including a ”5 Hour Baby Sweater!”), but blankets are quick, simple to make, and guaranteed to fit. Families can then continue to treasure them long after the child is grown.
It can be a great asset for when the child becomes a teen as this is usually a time when there are many differences between the parent and the child. Any kind of needlework which you share can help to eliminate differences, tensions, and arguments, and bring you closer together.