We've had to cancel J bookings once in the past due to medical reasons and did so a few days from scheduled departure. We changed the bookings to another date and took a small hit for changing the flights - £500 each from memory. We claimed this from the travel insurance and ended up not being out of pocket over the whole exercise but had other flights to look forward to 8 or 9 months later. If you get 'naff all' for cancelling is changing the booking an option to consider OP?