There is always a way to find the time to train for a marathon. Maybe I can give you my own situation so that you have some perspective on what it generally takes - and bear in mind that I’m training a bit more intensively than a first-time marathon runner would do.
First up, my (self-penned) training plan calls for running on six days of the week, with the Monday following my long-run day being a pure rest day (though I may do some stretches or walk the dogs along the beaches). Tuesday to Friday, I generally wake at 0500 and leave the house for work at 0530, getting back home normally around 1700 to 1830 depending on when I leave. If I’m running, I will then do my run as early as I can once home - at present I can manage 10 miles (just) before the light is gone, but this will reduce as we get into autumn/winter. For me, I run typically a 10K or 10-miler Tues, Weds, Thursday, and Fridays I often run in Edinburgh after work but before heading home. Saturdays - Parkrun. Sunday: long-run, either a ‘short’ long-run (with my wife or on my own whilst the kids are doing their sailing and done in time for them finishing) OR if my wife takes them I can do like I did yesterday and get a proper long-run in (yesterday’s 22-miler was fitted in by starting just before the family left for the sailing, and I was home and showered before they returned from sailing (around 1230)). Or, I do a 10k or 10-miler later in the day whilst the kids are at swimming.
It’s a tough schedule, but perfectly do-able even with a full-time job and ‘dad duties’. For example, Thursday is Taekwondo for my younger son, 1800-1900 at a local school. I can easily squeeze a 10-11k run in between dropping off and collecting. You just need to be organised and a little creative. I do have a tendency to fall asleep by about 2130 on account of the running and early starts!!!
If I can squeeze in a 50+ mile week of running, most people probably can. And for a first marathon, most plans top out at around 35mpw, so very achievable (if you genuinely want to do it). This past week, I squeezed in just over 10 hours of running around a full-time job and ran 64 miles of training.