There are so many diets and lifestyle plans, my suggestion would be to read through the forums and see if what others are doing is something that appeals to you. Or you can start by just making a few small changes (ie: cutting out unhealthy snacks/sweets.).
Also, if you look under the food category on this forum you will find some wonderful recipes others have posted.
Remember when starting out, anything that gets you up and moving can be exercise. I have a 10 month old grandson, I watch 2-3 days a week. We get on the floor and he likes to crawl under the dining room table, when he gets to the other side he waits for me to crawl under the table. Do I look ridiculous? Maybe, but it is only me and the baby so who cares. Lol. My point is that on the days I have him, that is my exercise. On days he is not with me, I have a regular exercise routine. When the weather is better, I put him in the stroller and we walk outside or at the mall.
Playing with your 7 month old is good for both of you..and fun!
Good luck, I hope to see you posting your progress.