Have you received tracking for the phone? If you have, the tracking will show whether the the phone has been collected from the warehouse
If it has, then delivery will be down to DPD, which currently states at https://www.dpd.co.uk/content/products_services/covid-19-bulletins.jsp
We want to confirm that all our parcel collection, sortation and delivery operations are continuing as normal.
We can also confirm that we are seeing extremely good service levels right across our network
If it has not been collected, then things may be more difficult. The government may consider a warehouse despatching phones not to be an emergency service. In that case, they too will be ordered to close, in the same way as shops selling electronic goods. But I'm not seeing a definitive government answer on that and so far giffgaff still shows phones for sale on its web pages.
ok201712 if I'm not I can make other arrangements.
Likewise, it's going to be harder to get a phone from a shop. Mail order still seems to be working at the moment, It's reasonable to expect that mail order delivery might take longer than usual and usual click and collect offices might be closed,