Go to a breakers yard and find an SRI then rummage for the interior. I had the Corsa B but
iirc the sxi/sri had different dials, gearknob and trim parts. Not sure about your seats but the sxi/sri might have better bolster support.
Flocking is a good idea, will cost you around £110 for the entire dash. And you could accent that with vinyl to cover existing trim (3M DI-NOC is good) or if you intend to re-spray make sure you do it properly with keying, thin coats and lacquering.
There are refurnishing companies that would be happy to cover your all seats in faux leather or different colours to suit you theme (if you have one yet

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Replacing all of the dash/heater panel/instrument panel bulbs with LEDs is a quick interior enhancement and gives you an option of choosing the colour. I replaced my dial bulbs with green LEDs and loved them, your options are pretty much endless.
Check the web for guides on removing trim parts and happy modding! Welcome to the site by the way, have a look around to find interior ideas and keep us posted on how you get on