First let me say
for running!!! I love running!! I've been at it about a year and I still do about a 10:30 mile.
You can easily google tons of info on running, so really most of what I'm telling you I read elsewhere.
Seems speed workouts are a way to improve time. Which is like intervals. Run/jog/run. Well, warm up slow, then run at a pace you can only hold for like 1-2 minutes, then jog slower again for a few minutes, and repeat. That is a very watered down version. If you google it you can find very specific interval workouts.
Now I have read on running forums that beginners, or people such as myself that were not active befor running and started out overweight, should just work on basic easy runs until its a regular part of their life. The longest I've gone without running is about 2 weeks, though that's not usual. Today, for example though is about a week that I haven't run. Then I'll run consistently for a few months (3-4x week) then miss a week. I was told by a certified trainer that is a runner, that you have about 2 weeks off before you'll see a decrease in your running when you do get back. I must say I see it after a week!
Are you running the whole hour? Or do you have to walk? If you are walking, the advice given to me was slow down a bit, and consentrate more on going further without walking, rather than faster. THe advice worked for me. Last year at this time I could barely run for a few minutes without walking. Now I can run easily an hour without walking. I never would have thought it was possible!
Also tempo runs are good for increasing speed, but google those as I will likely explain that wrong!
I would just work on making all your runs enjoyable so you want to do them and running becomes a regular part of your life. 4 months is a long time to miss and you will likely be back at square one after that. But just keep at it! Its soo much fun and worth it!!
Good Luck!!