Even as a British citizen who likes city life, London in particular never tempted me, because of both the nationally infamous housing cost and the un-fun experience of Tube travel.
All that combined means it's much easier / more enjoyable to do some work / read a book on your commute if you're using the bus, which for me was worth the extra journey time.
Obviously for longer journeys you still need the tube/train, but I lived fairly centrally so was able to either bus or bike 90% of the time.
If you pick the right place (look at the cycleways map), you can usually find somewhere with a mostly off-road cycle route from home to your office.
It's much easier to get a remote gig, so it seems like a location will no longer be a problem.
Like Romania, it has an almost impenetrable firewall of negative PR that isn't born out by the experience of living there. Yes, there's an ugly old ICI factory that covers several square miles (the emblem of the region). But everything beyond that is gorgeous, green and largely untrammeled. I shall never forget walking through waterfall-strewn valleys and splendid forests and meeting hardly anyone else except some friendly dog-walkers.
Plymouth was decent enough, but I was only there as an industrial placement student, so I’m not sure about non-student prices.
Aberystwyth is pretty, but tiny, ~4 hours from anywhere that isn’t rural Wales regardless of your mode of transport, and literally 30% of the population are students. I didn’t stay long after graduation precisely because of the lack of tech jobs.
Portsmouth area is terrible for the tech scene — I grew up close to there, my siblings still live nearby, but when one of them was job hunting they ended up getting one just outside Farnborough with a one hour commute.
Sheffield is cheap, but I was trying to be a self-employed game dev when I was there, so I can’t say anything about the tech scene.
If you still care about location for everything except work, there’s lots of pretty countryside on the South Downs, Norfolk, Aberystwyth area, and west of Sheffield. St. Ives (the one near Cambridge) is probably one of the best combinations of cheap and pretty (just be aware of the flood zones).