Perhaps you need to step back and look at what you would really like to do inthe future, then look at how you can achieve that, whats steps can you take to get you closer to that.
Do you have someone that can give you a second opinion, its very hard to talk yourself up on application forms when you doubt yourself even a little bit. Sometimes it call help to pretend you are talking about someone else when you fill forms out.
Ok you are not going to go out and get the perfect job tomorrow but you can start to plan a direction to head or even to try to see if it is the right direction. Lots of people chop and change and retrain these days.
Look at all the options voluteering, training, studying etc. See what funding you can get to do any of these. There are grants availible for retraining and even the Open University give big discounts for low/ non earners.
I am 30+ I have just started a foundation degree, I have had loads of jobs over the past 10 years including delivering pizzas, tidy greeting cards and working in sweet shop. Even if I don't get a job directly related to the qualification I am doing I know doing this course wil help increase my prospects anyway.
On a totaly different path I am also going to volunteer in the Citizens Advice as a lot of jobs on this route require knowledge of housing and benefits and this wwould give me that.
I take it you have kids?? Don't be ashamed about being on benefits many people are for all sorts of reasons and circumstances.