UK Car Repair Questions? Ask a Mechanic for Answers ASAP
You either have a half flat battery, or the immobilizer not reading your key correctly.
Is the car at home now?
If you turn on the headlights are they bright or dim?
If they are dim, you need a new battery.
If they are bright, there is an immobilizer problem.
Do you need any further help?
I hope my advice has been of assistance to you.