The form you were sent is very likely Lloyds version of the form used by many financial companies for PPI claims. There is a version of it on the Financial Ombudsman Service website.
It is intended to allow you to provide as much detail as possible about the policy, your recollection of the way it was sold and anything else that might be relevant. Of course, as the policy was probably sold years ago it can be very difficult to remember the details, so information has to be just whatever you can recollect.
For example, you may not recall whether you were told (almost certainly incorrectly, if you were told it) that taking the PPI policy was a condition of getting the loan, mortgage or whatever. But if you know your finances at the time were pretty stretched the likelihood is that you would not have taken the policy if it was made clear to you that it was optional. This is the sort of thing you need to be able to explain as best you can recall it.
Basically, the more information you can give the greater the likelihood of a claim succeeding – always assuming, of course, that you do have grounds for believing the policy was mis-sold. I would certainly look through the form you have and think about the questions on it so you are prepared as far as possible when you speak to them on the phone.