Redundant soon - discretionary sick pay

[Deleted User]

My employer pays discretionary sick pay. Basically, I get full pay
when I'm off work, self-certified for 7 days and then doctors note.

I'm being made redundant in a few months and things arent great at work at the moment. I've got a history of stress related illness and
want to make sure I dont do down this route again - especially since I've got a new job to find.

I'm just worried that if I go off sick in the time before I'm
redundant the company will assume I'm trying it on and possibly try
not pay me.

Could they do this even if I have a doctors note? I understand the
letter of the sickness policy is at the companies discretion. Or would they even bother doing this? (Its a large multi-national rather than a small one).