I was lucky with my insurance for our upcoming holiday as I pay for it through my bank account. Have often thought about downgrading my account and saving some cash. Am glad I didn't now. Basically it's a continuous policy so because we booked our holiday before diagnosis I'm fully covered.
Have you rung and policy providers or just looked online. The word metastatic makes them freak out but I don't think pelvic node involvement is truly metastatic (may be worth asking your consultant or CNS for clarification. I have always Bern of the impression that metastatic cancer is advanced (ie stage 4). Mine was 2b with bilateral pelvic node involvement. Such confusion.
It's possible that you may not be able to get insurance now, unless you take a policy that doesn't cover you for anything related to the cancer. This however won't be the case forever.
Keep looking. Ask at your hospital too. There is a support place at mine that have a list of insurers that people have used successfully. Unfortunately I didn't need to ask so don't have that list. Macmillan may be able to help too. Also try bigger companies like Aviva etc if you've not done so already, because they have more customers it spreads the risk.
Good luck, I hope you find something.