No but you can spread a sheet of black plastic over some of the grass and the grubs will come up onto the surface overnight and you can remove the, That's the theory anyway. Encourage your garden birds as some of them will pick them out.

I think the nematodes are generally available online. I'm sure I've read on here that they have a short shelf life, therefore not practical to be sold in GCs.
Having never bought them I can't recommend an online stockist.
Worth giving Steragrams suggestion a go, you'd probably be quids in if it works.

Nematodes commonly known as "round worms" are everywhere. These tiny worms are in the soil, the oceans, ponds lakes streams and can be found in almost every environ from the tropis to the arctic regions. Some are free living and feed off of decayed matter, fecal material or fungi in the soil. Some are parasitic and feed off of animals such as ourselves, trichinosis, being a good example or heartworm disease in our pets.There are nematodes that attack or carry viral disease to plants.Some are predatory, which is the nematode that you wish to know about here. Attempting biological control of any pest is very difficult, takes time and is only sporadically successfull. So I would try remedies such as steragram has mentioned. The nematode is the invisible giant in the world of nature and a little time spent in getting to know this life form would be well spent I believe. One of my best friends who recently past away spent his entire life studying these creatures and the effect that have in agriculture both good and bad.

google Nemesys - they do a range of nematode treatments for different problems, so look for the one that treats leatherjackets. Someone has already said they have a short shelf life and that's why garden centres don't stock them.