I believe if you pay extra for the benefit of a changeable ticket - then you should be able to change it to a date that suits you, but pay the difference. I know it seems like you could lose £200 but you may need to weigh up in your mind that it could also save you £300 (the DTV fee) if it goes well. The otherside is it could all go to pot, which wouldn’t be nice

Thank you for informing us of this and I am sorry to hear you are having to go through this hurdle.

It seems that the London Embassy is requesting a flight from everyone so far - from what I have read?

To echo what other people have said - can you not book a refundable/changeable ticket 4 weeks ahead, hope they approve and then change it back to the date if needs be? You’ll have to book a ticket out regardless?