I'm surprised nobody mentioned this about what you wrote here...
"Ive seen CC 2018 Photoshop discs on Ebay for £25 .. About $40 ..
Is this the only way out ?"
This would appear to be nothing but a rip-off (surprise, surprise - eBay) - Adobe CC programs are used with their monthly subscription; you download the software to your machine but if your computer "calls home" and finds out from Adobe that you aren't up to date then it will stop working. There really is no such thing as a CC2018 disk - you simply download the program when you sign up. So run, don't walk, away from that nonsense.
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