What brick do I use to build a fire wall?
Question continues: "The walls are 3m high by 4.5m wide by 0.2m thick, and supported at each end of the 4.5m I believe this will have a fire rating of 240 minutes? How do I support the wall for strength against wind? Are steel wire wall ties sufficient? "
You do not need a special type of brick such as a fire brick. I suggest a double skin masonry wall in standard imperial clay brick, with each leaf 106 mm in thickness. This will yield an overall wall thickness (unplastered) of 212 mm which will have a nominal fire rating of 240 minutes.
I would recommend supporting each 4 meter length of wall with a 340 x340mm brick pillar at each end, as well as using wire ties (brickforce) as suggested.