You are two years out of college with a good amount of savings. Now is as good of a time to quit as it ever will be. You are not going to have more time or less responsibilities going forward.
£25 * 30 * 8 = £6000.
This is not sufficient savings in London.
8 months' savings is nothing. Personal finance experts recommend saving 6 months' expenses at a minimum, for people who have no intention of quitting anytime soon.
2 years is the bare minimum for something like this.