Thanks guys.
Yes my old Vectra-C had hardened valves too, but didn't survive much beyond 100k before they burned and they were £150 each. I daren't think what these would cost new lol.
Ok Yes, it's not a chance worth taking I guess, especially as I already have a kit.
As for the filler type, yes I've seen lots of other cars with this Euro style and can't understand how they get it past their insurers either unless they aren't declared but seeing as my insurers already know about it and won't renew my cover without a UK certificate then I don't see a way out of it.
Oh Well, hey ho.