Thanks for the info!
Our host has said she will make sure we get a "full refund" on her side but admits AirBnB will likely take "something" - which I expect will be the service fee. EC policy says service fee is refundable but not past May which is just an arbitrary date...
Even so, for the host's "refund", we're only going on the host's word as the refund section doesn't have an option for covid-19 post May and doesn't include any mention of the host being involved - it just says we get £15 back and do we agree.