There is an excellent poster who I think name changed after the last security issue who quite rightly says cheeky fuckers get away with it because we let them!
She's thick skinned enough to be a rude sponger using your electric/heat/food/drink she can be bloody well thick skinned enough to take you telling her to pack it in graciously and if she doesn't cut her off completely!
Your toddler I promise you doesn't give a toss whether you maintain this friendship or not and even if they were old enough to give a damn that's no excuse not to deal with this chancer in no uncertain terms!
With your update plus your comments about her not feeding her child you need to be calling SS.
Neglect especially on this level IS abuse.
"Excuse me HV my friends house is a shit tip but she doesn’t think it is, her dc has only ever eaten vegetables when he’s at my house as “they are disgusting” apparently and his 4 teeth don’t get brushed. However he is a good weight, happy and warm.
Would they not think I’m just a dick?" This is not the whole truth though it's more like
"Excuse me HV (personally I'd speak direct to SS) but I have become aware of a situation that seriously concerns me, "friends" house is extremely unsanitary to the point that it's a health and safety risk to her child & others, the child repeatedly complains of being hungry, I've been told many anecdotes which strongly suggest hazardous neglect, basic hygiene and nutrition needs of the child I believe are not being met, she's admitted she smacks him and claims she has no access to family funds for basics like food"
I say SS rather than hv as I can see her refusing to engage with hv and they can't push the matter, whereas SS have a bit more authority, plus it sounds like things are pretty bad.