I’ve seen a few people posting that they haven’t been able to get on the vulnerable list for priority delivery slots etc. MIL is highly vulnerable and was having difficulty registering at the start of all this, so we ended up emailing her local MP who was incredibly helpful in pushing her case through. It turned out that her medical records hadn’t been updated correctly - they listed her as not having hypertension when she clearly does. Once we got that sorted she was added to the list and now has absolutely no issues with getting a delivery slot, which is such a relief!
Posting here in case it can help anyone else. Sending (socially-distanced!) hugs to you all!