What a nice site!
The only thing I didn't like was the "post your item" button & icon. To the uninitiated it might look like they have to send their tumble dryer through the post ;0)
Would it be better to say "list your item"?
My local council have a good section on recycling & link to the websites of local schemes, like charities that collect old furniture. It might be worth asking a few councils to give you a link on their sites, as you are offering a free service which will reduce landfill.
With the UK about to be fined for missing the EU landfill targets, this is a big issue for local authorities at the moment, as they are likely to be fined in turn by Government.