I hate to be the 'old guy' but if your profile & signature are accurate you are 20 and shooting for 120,000 GBP for FI, this may be a temporary adjustment period. Also, while I have studied the ERE path, I don't think it's sustainable if you want a family or have/get a spouse who's not 110% on board so there is a chance you'll need more that 120K GBP.
I went through this after about 12 months working full time where I was missing the "reset button". I no longer had summers off, new semesters to renew my interests, new projects but rather just the knowledge that work was going to be roughly the same day in and day out. I'm now in my early 30's and even though I have done a number of different functions, I still miss having my entire life/schedule 'reset' but you do become use to it. There is a reason working is nicknamed the grind.
Stick with it and find ways to grow your skills, network, and interests both from a career and personal perspective. As others have said, it's not a two option question, rather start figuring out what your 'next step' will be professionally.