You might have issues finding someone to cover her. I was told by my vet that most companies refuse to issue a new policy on a dog who's 8yo+, so I made sure to get my 7yo dog covered (and now that he's turned 9, his policy price has doubled, even though I haven't changed any coverage options or made a claim
).
FWIW I (now) spend about £65/mo covering my 9yo dog and 6yo cat. My policy (through DirectLine) covers up to £6,000 per illness/injury/disease (no time limit), with a deductible (called excess here) of £70-80. It does not cover preventative, non-essential, or routine treatments, anything for pregnancy/birth/tooth/gums, any food, or more than 12 sessions of hydro/physiotherapy. There's also coverage for accidental death, theft, etc, but I really hope I don't need those.
There's more information about their policy/coverage here (
http://www.directline.com/pdf/pet/P1014_1211_WEB_PDF.pdf).
I haven't yet made a claim, so I don't know how they handle that, but I will be filing a claim for long-term care/diagnosis/etc for my cat's weird skin condition.