if she's from a rescue don't they provide vet treatment for pre-existing conditions with their own vets?Celia Hammond Animal Trust has a long term fostering thing where they provide vet treatmentit means she was in a bad way when rescued poor little mite.
as I understand it the main thing is to know she might have flare ups so make sure she gets her annual jabs in future to minimise them. vets for pets do a life jab plans that's good value.
she might be of risk to any other un vaccinated kittens she may come across or house share with so if you don't intend filling the house up it will be fine
this shouldn't effect insurance as far as I can tell, just disclose it and they may put something in the policy - ask the RSPCA about it as they will be a broker for a few variants.
and morrisons or sainsburys chicken roll IMO.