I agree with the points made above and would definitely recommend looking online to see if you can source the medication at a cheaper rate. You still need the vet’s advice but why pay the middle man if you can save a bit by going directly to the supplier, especially if it's a long term condition.
I do my pet insurance through Tesco, two golden retrievers, and find them very reasonable. However as with almost all pet insurance the small print does mention a 12 month limit on any one illness.
As with every insurance there are restrictions and conditions that are not always made completely clear at the start. I always look at it as protection against any large one off vet bills but unfortunately have to accept that a long term illness will not be cover after a year. I guess it's kind of like car insurance were you can claim for an accident but not general maintenance work, not the best example but all I could think of.
I would consider looking online for the medication at a cheaper rate.