you may consider reed/pole screens, shade-netting, or canvas/plastic roll-down screens

My partner disguised an ugly fire by making an MDF 'cupboard' with a gap at the bottom, using 2 cm x 4 cm wood and MDF panels readily available from DIY stores, some of which will cut it to size for you. He is not skilled at DIY but made a reasonable job of it and I painted it afterwards. There are a variety of decorative panels, e.g. trellis or other cut out designs, so it doesn't have to be plain or expensive. The other option is to save a specific search on ebay or check on Gumtree. Good luck!

Hello, not sure if you have considered this or if it would work in your case but I was told by building regs that if you don't have fire doors for each habitable room you can have interlinked smoke alarms in each habitable room in addition to having them in the hallways. To get the electrician to put these in, it was half the price of having to change every door in the house to a fire door ( basic door with four panel design ). Obviously some people want to have expensive doors e.g. solid wood so these will add to the cost. If you live in a period proprerty you might not want to have smoke alarms drilled into the lovely decorative ceiling so perhaps you could have a mixture of smoke alarms upstairs and fire doors downstairs or just have them installed in a discreet place. Our electrician said they have to be minimum 30cm from the door opening.

Wayfair ?