OP I am sorry to hear you are struggling at the moment I hope next month is a bit better.
I think those who are saying this is theft or stealing without showing any sympathy should take a good look at themselves (I agree Mrs DV that there is a difference if someone is taking toys home etc without every replacing them). Secondly, legally this may well not be theft or stealing - its a funny world where the law is more balanced and shows more common sense than some of the posters
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Pendant alert
This is not necessarily theft or stealing from a legal perspective, if the OP replaces or intends to replace the item (or an equivalent as I think loo rolls would be regarded as fungible).
The definition of theft from s1 Theft Act 1968 (my emphasis) is
"1 Basic definition of theft.E+W
(1)A person is guilty of theft if he dishonestly appropriates property belonging to another with the intention of permanently depriving the other of it; and ?thief? and ?steal? shall be construed accordingly."
So the OP has the actus reus (guilty actions) "appropriation of property belonging to another"
but arguably does not have mens rea (guilty thoughts) "dishonestly" and "intent to permenantly deprive".
For example, if you honestly believed that the owner would consent if you asked then that is a defence to dishonesty.
Intent to permanently deprive is difficult because you have used the particular toilet roll so it is not capable of return but if you intend to replace with something identical (when the item you are returning is not of a specific nature i.e. all loo rolls are roughly the same (could be seen as a fungible asset) but there is only one Mona Lisa)