You're right, it's not your fault. And how you give birth *is* your right.
But if they don't have anyone available, that's literally just how it is. Rights don't come into it when we're not in normal times, everyone's just doing their best with a bloody horrible situation. Can't magic up staff if they don't have them or they are already occupied elsewhere. The pandemic fucking sucks - take it from someone who lost a loved one to it and is still broken with that loss. And the NHS staff are pushed to the brink with it now, not only are they going off sick with the virus itself, but also the stress of what they've been through and the excessive workload and all the rest of it. Then throw in the ridiculous amount of lockdown babies - we've all been busy bees while stuck at home - and they are stretched so thin its unreal.
So if the midwives are all needed at hospital - where they can support three or four women at once, including those who have higher needs and risks - over homes where they can only do one birth at a time, then it's entirely understandable. They need to be where they are most needed and can do the most good, and that's hospital right now.
Absolutely sucks for you if you don't get your planned birth, but still perfectly understandable.
Really do think someone should have made you aware this could happen though, given you the chance to find a private doula or midwife instead - maybe that's still an option, make some calls and see if you can get one? Last minute shutdowns and changing plans are the absolute worst and this should have been made clear as a possibility from day one. Agree they've completely let you down there and this is stress you absolutely do not need when you should be calmly readying for baby.
My friend had her little one at home recently, no midwives available but she just called the ambulance when baby was nearly there. That's always an option for you even if they can't do the full home birth. And apart from a few hours in hosp after for stitches, all went great.