Does amyone know where I can buy some szechuan pepper plants? Have looked at
all the usual sources but nothing is listed?

Thanks

These people sell both plants and seeds.
Agroforestry research trust fruits nuts seeds plants publications
For plants, you'll have to wait until the autumn. The seeds need 13 weeks cold stratification, so rather tricker than tomatoes then. I don't know whether the seeds in my spice drawer are as good!

According to Zanthoxylum simulans Szechuan Pepper PFAF Plant Database its dioecious, and not self-fertile, so you'll only get seed off the female plants, and then only if you have a male to fertilise them. Though curiously it also talks about there being "a plant" in the Cambridge Botanic Gardens and it fruiting heavily. Sounds like needs a bit more research to discover the true situation fertility situation.

Szechuan pepper is easy to buy as a spice - I bought 500g from a Chinese shop which has lasted me years even though I routinely put it in the pepper mill to mix with the black pepper - need a good quality pepper mill for that though. Tasmanian pepper, (which is definitely dioecious, btw) I think is perhaps more promising for growing an unusual spice in the garden in the UK, as the plants are much smaller, evergreen and rather attractive: Tasmannia lanceolata, but often sold under its older name Drimys lanceolata - mine has come through the recent winter with leaf damage but thoroughly alive, though I only have a male plant.