Rob,
To add a little to Paul Bearman's comments, Makrolon and Lexan are trade names for polycarbonate which should give you a service temperature of around 120 deg C, compared with around 80 deg C for Plexiglas acrylic.
Both are available with a 'hardcoat' surface which would reduce abrasion damage and improve chemical resistance. Polycarbonate is prone to chemical induced stress cracking.
There are many stockists in the UK but, to get you started, you could try Amari Plastics (I've no connection)
www.amariplastics.com They have a national network of branches and could probably recommend a local fabricator if required.
Jim