I resonate with this as I type this from NYC, a city significantly more nature-starved than London. I was pretty impressed with the parks and greenery in London. My friend there bought a unit in the first floor of a townhouse with a backyard in a peaceful but convenient neighborhood. Such an apartment would cost at least double in NYC and those sort of places are rare.
I'm definitely not a rural person, but I do think that living in nature has a strong correlation to happiness. I don't think the average person in a concrete jungle like NYC is happier than in a random village in the Amazon jungle or the Swiss alps. I don't regret my time I lived in NYC though other than that I stayed too long. It's fun for a time in one's life while one is young, but it's not a forever place for most people.
Most jobs suck. "Find your passion" is bullshit career advice because a job by definition means selling your freedom (if the job was so much fun they wouldn't need to pay you because people would do it for free). Unfortunately the reality is that we must make money to afford a modern lifestyle, and thus if you want financial freedom you will probably need to get a job (yes you can create your own business, but until that takes off you need to pay the bills somehow).
I quit the rat race and left NYC to travel the world. After 1.5 years of traveling I started to run amount of money and I reluctantly decided to start working again - this time remotely. But to my surprise I found that I actually enjoyed the new job and had missed having that sense of responsibility (or maybe I liked finally seeing my bank account balance go up and was trying to rationalize it, who knows). But eventually the job started to suck as I realized it was a deadend job and felt like I wasn't respected. I was miserable and performing the job was a chore, but I stayed because I didn't have the courage to quit a job that paid so well for so little work - the same position I was in in NYC before my world travel.
Finally that contract ended, and I was again free from work obligations. This time I set my goal to create my own tech projects with the hope of eventually monetizing them and living off of that. Finally I enjoyed programming again because I was building whatever I wanted.
A job fell in my lap with another startup, and I initially didn't want to take it because my focus was on my own work. But in the end I decided to give it a chance as I figured it could be a valuable experience, and I can always quit if I don't like it. The job turned out to be awesome. Awesome people, interesting problems, and I get a front row seat at an early stage startup. The downside of course is that I have not been able to put as much time on my personal projects as I'd like, but I am still working on it on the side, and we'll see if I can manage them both.
Leaving the rat race to travel the world led to some amazing experiences with high highs and low lows. I went from being sick of software engineering to wanting to build my own tech startups - which is my main work goal now. It took me traveling so much I got bored of it until I got inspired to want to build tech things again to solve my own problems. But maybe you'll leave forever and prefer being a park ranger in the words - who knows. We're all different.
In any case I think people should do whatever the hell they want, as no money is worth wasting one's life in misery. Worst case scenario you don't like living in the nature and can return to London to work at another bank with a renewed sense of gratefulness. Of course most likely you probably won't ever return to the same exact old life. Maybe you'll work remotely for a startup from the woods, or become a writer, or go completely offline and just live a simpler life. Who knows. It doesn't matter as long as you're doing you.
Either way best of luck on your journey, from one rat rat escapee to the next.