View on calling it quits - IB £300k pa

I’ve been with an investment bank since 11 years, now at the upper VP level and feeling like calling it quits - without having a proper backup plan in place

Feel like I need to rediscovered myself, interests and outlook to life - over the past couple of years have just become more ‘reserved’ and being fully absorbed in work makes me sometimes feel like I’m missing out on so many finer things in life like quality time with partner, baby (who was born a year ago) and ability to decide where I spend my time

35 M, base pay 160k + bonus of anywhere between 100-150k per year. Partner is self employed and making under 20k a year now given the baby. Don’t expect her to start making much more than that in the near term as focus is on baby.

Current outgoings roughly 5k per month might rise to 6-6.5k over time for child support/nursery etc. Mortgage of £800k outstanding with a on a 70% LTV, no other debt with a 3k monthly payment. ISA fixed bonds, cash savings of £400k, stock and shares in US tech £200k, Pensions £200k in diversified world equity. Idea is to transfer more of the cash ISAs into S&S over time as they mature to get larger exposure to equities over time (currently the cash savings and ISAs are in excess of the mortgage rate hence instead of paying down was simply saving up and nipping the 2-2.5% differential) while having no risk on the capital and accordingly repay part of the mortgage in 2027 when the fixed low rate ends depending on interest rate environment at the time.

Am I being irresponsible for simply wishing to call it quits and figure out the ‘next chapter’ in my life in the above situation or shall I just suck it up and stay on in the job for sake of the family etc. (it doesn’t give me any satisfaction or happiness anymore, more so my partner has noticed my behaviour changes being more irritable, unhappy most of the times when I’m home etc)

I’m thinking I’ll do a combination of study / exercise / look at other opportunities to try and do something self employed if I quit although I’ve never not been in a job with an income coming in hence the nervousness - coupled with a sense of responsibility now that we have a baby

FYI also have roughly £1m in an overseas property without any debt via inheritance which provides roughly £2k additional income per month post expenses etc

Any advice greatly appreciated!