Plastic canvas alternative?

has anyone got any ideas for an alternative to plasric canvas?

I'm making this: http://www.etsy.com/listing/102043152/c ... orage-tote

and I need some large pieces of plastic canvas for the inserts on the base and sides but I haven't found any large ones here in the UK.

I did think of using cardboard instead but thought it might get broken/folded with use.
has anyone got any ideas pls?

thanks in advance

is it called plaster board that thin bendy stuff from diy shop might work

attach multiple pieces of plastic canvas to cardboard so is rigid but wont bend

other than that ask in a craft or art shop for ideas x

What size do you need?