Make your own...
If your wall is uneven you start by fixing 4 or 6mm MDF to the wall, The main frames are basically just straight pieces of 12 to 18mm MR-MDF for the top and bottom rails and more straight rips for the upright stiles. This forms the "frames". The top moulding you see there is just a rebated dado profile planted onto the top of the upper rail. The panels there are moulded-out with a bolection moulding, mitred in the corners and pinned in place. Finally a Victorian skirting is affixed to the bottom. Pretty much all the mouldings used in a job like this can be had off the shelf. Main tools are a portable saw, a mitre saw and (ideally) a 2nd fix pinner (nail gun)
Because every house is different, you can't just buy a kit to do this - it simply wouldn't work. This is bespoke work, made-up on site, which requires the services of an experienced joiner ("carpenter" dahn sarf), especially where you need to take the panelling up a staircase and round awkward corners. Try to find someone who can show you examples of their work locally - this is not a job to hand to chancers
Or you could just DIY...