I did it. I have run for 30 minutes 3 times and achieved what I set out to do.
I can't really believe it as I thought I was too overweight to do any exercise. If anyone is reading this as a new runner, YOU CAN DO THIS. If I can, honestly anyone can. Keep going, trust the plan and stick to it. This forum is a God-send, use it and listen to the advice and encouragement people give you. We are a community and it is so exciting to see other people achieving their goals and helping others do the same.
Thank you everyone for your cheerful comments and consistent encouragement - I really appreciate all of you!