HR person here that sometimes has helpdesk positions to fill as well. Absolutely appropriate. Like others already said, you are better dressed than most people we interview for such positions.

Piece of advice if you don’t usually dress like that: Wear those clothes for a half a day going grocery shopping and doing regular daily shit. Helps make you feel more comfortable in them. Just give them a check up to see if they got dirty afterwards.

On a personal note, great choice of colours too. Best of luck to you!