As Perki has said, there is an online version that you can download from the directgov website which you can fill in at your own pace and under no pressure and then print off when it is finished.
I would also suggest joining benefitsandwork (about £20 for the year) and using their guides to filling in the form as they are very good.
Although the form itself seems quite easy to fill in, to have a successful application it really does help to know what is behind some of the questions asked (i.e.that the activities should be repeatable in a timely fashion without causing pain or breathlessness) and that it is important to consider what you can/can’t do for the majority of the time for fluctuating conditions and provide explanations in the boxes provided.
If you can’t manage the subscription message me and you can use mine to download the guides.
Best of luck hun,