Hi John and welcome to
the c5 site mate.
Like Chas says, a few pictures of what you are up against would help. You are quite right to query the availability of spares. Some parts are getting rare,expensive or just unobtainable.
If it ends up looking as though yours is beyond restoration, and the "c5 bug" has bitten you, there is always the option of selling yours for spares (helping to keep a few more on the road) and putting the money towards a better one. Just a thought.
It has to be said though, that saving one from being scrapped and restoring it feels almost as good as riding around in one. Gives you that "C5 grin"