I went through labour alone without dh two weeks ago.
He looked after DC1 and DC2 and I went to hospital by tram then 5 minute walk - I was only 3cm on arrival.
Despite it being DC3 I did not give birth til 10 hours later. I had a book and a birthing ball for company 
In some respects it was the right thing to do as DC1 and 2 were just as traumatic and DH could not really do much apart from watch in horror.
But I really didn't want anyone other than him there, equally similar to you my youngest needed him so I bit the bullet (Do not live in UK btw so no family around).
What can I say? I survived. But I wouldn't recommend it unless you have no choice or have experienced labour before which was not excruciating for you. I had no support or advocate therefore had to rally against having induction drip alone, have enema alone, left on a heart trace for two hours alone, have waters broken for me alone, you get the picture.
The hospital knew in advance I would be on my own but they thought as it was DC3 despite interventions for DC1 and 2 that I knew what I was doing so I spent 8 hours out of ten on my own basically then the last two thinking I was going to die. Natural birth without epi, pethadine or even gas and air SUCKED BIG TIME. I cannot get over how stupid I was or how brutal it was.
This is noone's fault, I accept that, and I also know my DH could not have done much had he been here but to do it alone you really really need to be strong, have a good/established relationship with the midwife or a high pain threshold imho.
That said, in the old days it was normal for my mum etc to give birth alone/with whoever was on shift and no doulas, advocates etc
I have a beautiful son. I could not be more grateful. But I would not wish what I went through on anyone else.
If I had had an epidural and/or not felt assaulted by the midwife I might feel differently. It may be very liberating/empowering for you to do it on your own. It depends I think about how much control you have over the circumstances.
Good luck with whatever you decide and do not let my bad experience put you off as like all births, yours might be a very different experience to mine. I thought it only fair to warn you that you cannot guarantee a quicker birth or a gentler midwife etc and the loneliness was hard to take for me when usually I am fairly upbeat/self-reliant.
