I think you could break a suit up into separates as well...harder to pull off the odd jacket but houndstooth flannel trousers + navy SC is badass.
Minnis 656 Houndstooth Flannel with No Man Walks Alone - Page 4
If you are planning on a 2-piece single breasted suit then 3.5 meters will be sufficient. You can order 4 meters if you want to be cautious.
I would recommend 5 meters so you have 3.5 for your suit and 1.5 meters extra for a second pair of trousers....this way when your first pair of trousers wears out you can keep using the suit for many more years.