Whenever I have had a exercise gap I like to start with yoga - mild strength , balance and flexibility which I feel helps prevent injury
These are aYouTube as it's often easier to do something at home when you get a half hour , and it's cheap
Yoga with Adrienne on YouTube - try the 30 days of yoga series
Weight training is an all round good thing - you can start with body weight but I have bought sone dumbbells from Argos
Amy body fit on you tube
I also do sone running - something cardio is good. Running is easy to do anywhere - take the kids to football and run while they play
Running - couch to 5km may give you structure - but may be a bit too much with family to look after - I'd start that a few weeks after doing a fair but if yoga
Do each once a week and it's a great start
Running is basically cardio - you might like to try spin ( bike ) or dance classes instead , or HIT or swimming - it's all about finding what you like best as then you stick. At it more
Circuit training or another type of weights class can be a good way to learn form - and you get a range of weights to experiment with