I tried through my Nationwide Visa credit card and they were useless. I actually found them far more annoying than YGT, as I understand where YGT are coming from. The credit card people basically said that they go by whatever terms and conditions YGT offer and that's that. I think the truth is that because this is such a crazy situation, everyone is making it up as they go along. That includes travel companies, insurance, and seemingly Nationwide/Visa.
Whilst I got a refund for my flights, a friend of mine was due to go to Australia in a few days through Emirates. I told her not to worry and when the flights get cancelled, you'll be offered a full refund. Emirates are refusing a full refund because they have said the only reason they're cancelling is due to government imposed restrictions, and it is not their choice. Her options are a partial refund of £400 (flights were £1000), insurance option minus a weighty £400 excess, or credit for a later date.