No idea as to your specific site/reviews as I’m not UK based, but, in general, here are some options…
Without knowing how much storage you need and what kind of workflow you typically use, its tough to provide a detailed response, so, here are some generic thoughts.
First, it’s a year old, but this isn’t a bad place to start. Andy and I talk about storage at the 37 minute mark.
On the low end is a single SSD or NVME in an thunderbolt 3 enclosure. I like Samsung SSDs and NVMEs and if budget is an issue then Sabrent NVMEs are a good compromise. Heck, you can even assemble your own with something like this… https://eshop.macsales.com/shop/envoy-express/thunderbolt-3. Turnkey would be something like this… OWC Envoy Pro SX - Thunderbolt Bus-Powered Portable SSD
Stepping up is some kind of external thunderbolt 3 chassis that has x2-x4 NVME sticks in it that you can RAID 0. This will give you 2-16TBS and something in the 2500Mb/s range. That would be something like this… OWC ThunderBlade
For backup, and, here’s the kicker, you should ideally have 2 yes 2 local backups of your data and one offsite. A common direct attached storage solution (DAS) is something like these… OWC ThunderBay 4 - RAID Thunderbolt 3 External Enclosure . At minimum you’ll want 4 disks, 6 are better, 8 is even better, and 12 is way better. RAID 5 them at a minimum, but preferably RAID 10 them. Lotsa people like the Ironwolf Pros as disks. And 8-10TB is the sweet spot for $/TB at least in my region/shipping/experience.
Don’t overlook a simple NAS either. Synology makes a ton of super great affordable NAS which you can easily setup Snapshot Replication to have 2 local copies and cheap cloud storage of a few TB wouldn’t be expensive, and you could likely hide them in existing Dropbox or Google Drive subscriptions. A couple of 4 or 6 bay options would be great. There’s a few super cheap 10GB option switches which would get you sorted quickly.
I know you dont want to hear this, but, I recommend getting 2 of whatever you decide. It takes the pressure off of early data hoarding and keeps your data protected from operator/hardware error. And, if you do amass quite a bit of data, a 2nd local copy is a few minutes away from being restored instead of hours/days/weeks of restoring an offsite backup over the internet over typical home internet speeds.
Hope this helps.