How much brake fluid?

[MACCAA]

Usually best to get 2x 500ml bottles.You may get away with one,but it's always handy to have some spare for post-Track day "bleeds" where required.

[Jmac]

1 ltr, 250 per wheel. And there is a completely different method to bleed the polo compared to the rest in the brand. Most of all cars i do furthest away from the mater cyl and work forward, Gti starts at front left, front right, rear left then rear right. Now this is for bleeding if the system has been opened ie fitting big brakes etc.
If you stick to the conventional method if only flushing you should be ok. If you find the pedal doughy then resort to the above, had great results with it
Cheers
Jmac