Hi @Joe1234,
A warm welcome to the Bunnings Workshop community, and thank you for your question.
Your jarrah floorboards are beautiful, and I am so glad you are planning to restore them instead of covering them.
The process to restore your floorboards will start with punching the nails below the surface of the boards using a nail punch. This is to ensure the sander can run over the floorboards without damaging the paper or the drum.
You'll then use a Floor Sander for the majority of the area, a Floor Edger against the walls and a detail sander or manual sanding for the corners. Make sure you call ahead to check the availability of the for-hire floor sanders at your local store, as they are often in high demand. Check out How To Sand Timber Floors for some guidance on the process.
Once sanded, you will have to fill the gaps between the floorboards. Traditionally, this is done by mixing the sawdust with PVA glue and spreading it over the entire floor so it fills any gaps. This method will give you the best colour match possible. You can also use Timbermate Jarrah Wood Filler if you'd like, but mixing sawdust with PVA glue is the traditional method that ensures a good colour match. Once it has dried, you'll give the floor another quick sand to remove any excess filler.
After this, you'll want to clean the floor to remove any residual sawdust. Thoroughly vacuum the floor to remove as much sawdust as possible, then follow up by mopping the floors. Once dry after mopping, give it another vacuum to ensure everything is picked up.
You'll then apply a floor finish to your newly sanded and filled floorboards. Check out the range of Wood & Timber Polish for a variety of products that can be used. Check out How To Seal Timber Floors for some guidance.
Let me know what you think, and if you have further questions, please don't hesitate to ask.
Jacob
