I will be making arena walls that will either be 1m or 1.2m long and 150-200mm tall, and there will be a minimum of eight sections bolted together. So a 1.2m x 1.6m piece would provide enough for us to clad the walls of our smallest setup, but we'll happily take as much as is available/we can afford

If there isn't any polycarb kicking about, we'll get some HDPE (non-transparent isn't a problem as the walls are low) but that would be our second preference.