So the disc tab looks the same as mine now I'm looking at the pics on a monitor and not my phone. Looks like a Hope headset in there, which is good - and should do you well.
Original paint would have been sprayed, and there was also a nickel finish. The 1997 catalogue is linked below, although there is often some crossover with 1997 dated frames being built into 1998 bikes (mine is)
https://www.retrobike.co.uk/threads/orange-bikes-catalogue-1997.279654/
Orange themselves provide a service to respray/finish frames - they put them down the same line as the new bikes, but only use the current colour palette. Finish is very good, as you'd expect. I recall the cost being about £250-£300 from memory so way more than any old P7 frame is worth (yours around £50 given condition, but more with the headset). Mine has sentimental value so I was prepared to spend.
https://www.retrobike.co.uk/threads/1998-p7-retro-british-kit-build-ss.443221/
Powder coating is probably a cheaper option and brings up a choice of colours. You can do a lot of the prep yourself in respect of sanding back and rubbing down. Also gives you a chance to inspect the frame for any damage/rust. A search on here will likely bring up some pointers etc.
Good luck!