I would check the Etsy site. Many vendors deal in new and vintage clothing, jewelry, scarves, etc. Prices are typically much less than department stores. Here in the US there isn’t anything particularly noteworthy about the packaging, but you may want to check or even request a specific packaging arrangement.
One thing that they are doing here is that Amazon and others are setting up pick up sites. For example, Amazon might make an arrangement with a department store to be a pick up site. I would imagine you present identification and perhaps your E-mail confirmation message and your package is released to you directly. It never gets sent to your home. I believe someone mentioned that they had started the process in the UK also, but I can’t say for sure.
We have a search utility here so you can search you other UK members. Click on Social in the menu and then Member Directory.
I also encourage you to complete your Profile page as best you can. It helps others to understand where you are on your journey and where you might need help.