If I wanted to run the London Marathon 2019...

[bibblebobblebubble]

... what should I be doing now (and is it even realistic)?

I know there are marathon training plans but they are for a certain number of weeks.

I run now but only about twice a week, 5k a time. Longest I've ever run is about 7 miles but that was over a year back. I've had a couple of injuries so doing strength exercises now to avoid it happening again.

Is 2019 a realistic aim? Or should I be looking to half marathons for now to see if I can manage them, and then look to 2020 for a full if so?

The strength training is definitely a good idea. I would try to run 3 times a week if you could, I think it is a good idea to do a couple of half marathons. I think you can learn so much about your body, how it responds to training, how much rest you need, what nutrition works for you from doing some longer races. Then 2019 would be fine, either the ballot if you get lucky, or a charity place. Good luck and enjoy!

Harder than running it is getting into it!

Definitely start entering half marathons