Where can I get these in the U.K.

Im going to make a screen for the use of SCROGing but because of my limited space I must use slim poles (instead of wood pieces).
Ive found the perfect frame & connectors: Homebox, Budbox & Secret Jardin hydroponic grow tents

However the poles are metal & too long so cutting it down to size will be a hassle.
Where can I get the same poles but in PLASTIC?

Garden centres sell shit like that for building lightweight greenhouses. Or you could just get a hacksaw, it'd probably be just as easy to cut the metal tubes imo.