Reconstituted chip foam can often be supplied by a local upholsterer but emphasise the need for it to be 10lb quality. This should last for 40-50 years. Some suppliers try to tell you that 6lb chip foam is suitable. It is not. It will collapse in less than 20 years and most people find it too squashy.
You can almost certainly find local suppliers for hard-wearing cloth for the base of your kneelers, strong thread for making them up and nylon tape for hanging them, but if in difficulty try the following:
The Cloth Shop – View site – Heavy calico or similar
Macculloch and Wallis – View site – Tape and strong thread
Amazon – View site – Curtain rings & D rings – Also see your local hardware or haberdashery
Software can be useful for giving stitchers a coloured design to work from – though most find graph paper, pencil and rubber much less fiddly. But why not be modern? Give it a go. PC Stitch has been used successfully by some congregations recorded on this website.