I would go straight for the practicalities.
Draw up a list of each assigmment task, when it's due, its weighting within the module, and an assessment of how much or little work has been done already.
Create a priority list which should refect the importance of each task. The one with the highest weighting, the least work done and is due the soonest will go at the top. The task with the lowest weighting, most work done and due the latest will be last. Categorise every assignment task and add them to the list. Use this to focus your efforts.
Create a schedule - basically you will need to work flat out from now, with time for rest obviously. You need to clear the decks really.
Asking for an extension - are you sure you can do this as normally the deadline is the deadline and if you submit late you would have to submit an EC application with supporting evidence. This will certainly be worth doing if you have acceptable reasons as it will give you an extra week.
If even thinking about doing these things are stressing you out to the point of inaction, then you really do need to speak to your Personal Tutor wh will be able to direct you to the apporpriate support within the uni.