DottiestDoris Go for it! Yes you ought to plan it a bit when you might be able to fit your runs in, so that you don't fail at the first hurdle.
First time I think I started in the summer holidays, in the summer, I had the app and the running shoes ready since spring! But once I started I kept with it, and you can too!
At the start you really only need 30mins or less from leaving our house - most apps tell you the total workout time including warm up and cool down.
At the beginning I managed to do one run on Sat during the day, one on Monday after dropping DD off at nursery (not working Mondays) and then another on a Weds or Thu evenings, after DH had come home from work. The only problem with evenings I found was that if I didn't dash out at 5 or 6 then it got really late as you really need to wait at least an hour after eating a meal. But I used to meet a lot more runners in the evening at 8pm than I do now at 6am, so that seems to suit lots of people.
Get your family on board to watch the kids, especially if they want you to find an alternative to 5:2 (but be aware that running might not have the same effect, but I'll be great for your fitness)
My first year of running, by the time winter came I was so fired up and proud of having kept it up that I ran though all the winter including ice and snow. Then you juggle your days to fit running into daylight hours, as early mornings or late evenings get a bit cold...
Right now I run early morning, 3 weekdays, I have to be back by 7am when DH leave the house. One of my kids still wakes up at 6 too but can occupy themselves now till I get back and daddy makes them breakfast.
To keep going in the long term: find an event to aim for, a reason to keep it up - I think next year is Sport Relief year again, you should be able to find a 'Sport Relief Mile' event near you in March (you can do 1-3-5 miles I think). And Race for Life is in early summer too, they have lots of races all over the place.
Good luck and come back here see find plenty of people who are in the same boat. Missing a run is not the end of the world either, you just pick up where you left of or repeat a day / week until you feel comfortable to move on.