If you've got an NA, any pump from a 1989 through to the end of production will suit. TT's built from 09/1993 to the end of production are fitted with the same pump, so you could also use one those. If you have an early TT built from 07/1989 up to 09/1993, you'll require a TT pump from that era.
Hi Max, I have a good working TT power steering pump from an 89 Z. Located in Melb, but happy to post. Could your PM me your postcode so I can work out a postage estimate?