Thanks for replying wardie!
That's what I've been doing... until now. (FYI, I've had a few SSDs and HDDs in the past. All but Seagate's died. So, I only trust Seagate) The biggest desktop HDD they make is 10TB. So I'd have to buy 2 and clone them. That would be around £450 and I'd have only 10 TB actual storage. Mind you, I'm producing 7TB of data in a period of 5 years. So that set up would keep me going for about 6-7 years.
On the other hand, a RAID array would save me from all the hassle and the clutter. I've just stumbled upon OWC's Thunderbay 4. For around £1k (using 4x Seagate BarraCuda 8TB) I could have a RAID 5 array, with 24 TB of actual storage. My data would be safe, the set up would be good for maybe 15 years, and everything would be taken care of by OWC's software (Softraid). Does that make any sense?