Can someone tell me what I need to show up with when collecting my new replacement UK passport at the Trendy building.

I assume I don't have to make another appointment?

Based on 3 passport renewals done back-to-back about 2 years ago. They sent an mail when the new passport was ready for collection and I needed to show this email at the VHS reception in the lobby downstairs before going up. Showed it again at the VFS front desk before they let me through security screening and wait to be called in. I also needed the receipt and copy of the submission checklist that they gave me at the time of submitting the application before they give me the new passport still in a saled envelope to check for correctness before I signed for it. If they let you keep the old passport while the replacement was being processed, you will need to surrender it for invalidation (cut off the corners) before they hand both the new passport and old one back to you.