Of course it's not too late! You're early 30s - you could have another 30 or 40 years before you retire!
Think about your current and past jobs, and any outside activities.
Think about all the different tasks involved, from the daily/weekly admin tasks, to whatever attracted you to the job in the first place. Consider things like the physical environment, the location, the hours, the commute... whatever else.
For all these things, work out which ones you definitely want more of, which ones you'd prefer to have (but wouldn't be a deal-breaker), ones you aren't bothered either way, ones you would prefer not to have (but again, not a deal-breaker), and those you absolutely couldn't bear.
This should start building some sort of profile about what your ideal job might look like. Then you can start looking at the sort of jobs which fit that. (This is the trickiest part, IMO, because it's not always easy to tell which jobs would fit, unless you already know about them, and if you're looking to change careers...)
If you can afford to consider studying again, then it might also be worth considering a careers counsellor.
(Also consider any restrictions - e.g. mortgage costs mean you need a salary of at least £x amount, or children's schools or ailing parents mean you need to be within an hour of X town, or you need to be near public transport links or whatever.)