Large heavy duty plastic sheet/bag (Nether Stowe WS13)

I’m looking for some large plastic bags or sheets (like those that a new single mattress or various other new items, is wrapped in) or an unwanted tarpaulin.
For protecting the single person wooden chair and 3 person wooden bench that I renovated in the Spring. A shame to leave them exposed to the winter weather. I can collect from Lichfield area. Thanks