HI Lucy
It is absolutely fine for you to post here!
It is up to you what evidence you send in, but you want to make sure that whatever you send in is relevant. Unless the receipt has some relevant information on it, pertaining to the PIP criteria then you don't need to include it. PIP isn't about your ability to work, it's about how you manage your daily living.
I would have a good look at the pip guide when you're completing your form
www.benefitsandwork.co.uk/help-for-claimants/pip BIS
