Supply and fit 6 internal panel doors. Use existing handles and locks for 5 of them.

There is a large choice of doors, but if you want to keep existing locks and handles, that may limit your choice. Aside from that any internal door will suit. The door stops as they are will most likely allow only 35mm thick doors. You will need to get someone to have a look to assess the frames and ironmongery and of course your tastes.

use lightweight 6paneled doors from any diy chain approx £25each can also use same pattern but a fire door (dearer) if req