25min commute ok? (London)

By what exactly (e.g is it longer at night in a cab)?

Irrespective of the above, I think 25 perfect-I didn’t like being too close when I was junior-like the separation, nor do you want to be too far obviously 

What is the cost of living differential? If you're saving a lot on rent, 25 min is fine but definitely on the higher end. I keep it in the 10-15 minute range

Job Satisfaction vs commute time. 

https://www.inc.com/business-insider/study-reveals-commute-time-impacts-job-satisfaction.html

Also a junior in London, I went from 18 min commute to 35 min in exchange for double the bedroom space at 66% the cost. Absolutely much happier now than I was living in a shoe box in Holborn. 25 min should be absolutely okay.