I just had my PhD viva last week and I'm happy to say that it went very well: it was one of those great times in life when the best case scenario comes true. I did notice though that there was very little advice (that I could find) specifically on English Literature PhD vivas and the finishing stages so here are some of my thoughts on the matter. My PhD was on science fiction specifically, so I had various fields to consider in advance: my author (William Gibson), the field of science fiction studies, the various theories that I'd brought into each chapter, critical theory and philosophical issues. This could feel a bit overwhelming at times, but I managed to get through it without too much worry.
In a lot of the advice I read about vivas in preparation for my own they emphasise the importance of a good PhD thesis to the viva process. Of course, having a good thesis is the best way to stand yourself in good stead. However, recognising that your thesis is a good one can be difficult after the years you've spent on it and the fear that may be building as the viva approaches. I found that the nature of viva preparation brings your focus to the shakiest parts of your thesis. I'm not just talking about the places where your writing falters, or where you've misspelled someone's name - I'm talking about the parts where you've used a theory that you don't know encyclopaedically, or where you name-dropped a novel in the 'Future Research' section that you haven't actually read. Focussing on these shortcomings or wobbly areas can make you feel like you don't know much. You need to bring your focus to what you do know if you start feeling overwhelmed. This is the vast majority of your thesis, the bulk of your original work, and the topic your examiners will ask you about in most detail. I found it helpful to run through these questions the day before, it really made me realise how much I had to say. If you can manage these questions in a relatively fluent way then I think your viva prep is done and it's time to relax and get some sleep.
The most important thing to do in the days running up to the viva is to stay calm. I was in a strange situation at my viva, in that one of the examiners was having some problems which threw his availability into doubt. I had a phone call the day before warning me that we might not be able to go ahead with it at the scheduled time - in fact, it might have had to be rescheduled for after Christmas. Needless to say this uncertainty was not welcome in the moment, but it did allow me to stay calm. Every time the nerves started to ramp up I just reminded myself to cheer up, because it might not even happen. Of course, not everyone finds themselves in this position and most people wouldn't want to, but it might be a useful tactic to imagine that your examiners may come down with a flu and have to cancel - this way you can stop yourself from freaking out more than necessary.
When I was talking about the viva with my dad and my sister the week before I mentioned being nervous about being asked a question that I had no idea how to answer. My sister suggested that I bring a pocketful of glitter with me and throw it in the examiners' faces to confuse and distract them if I was at a loss. I did have one 'glitter moment' when I was asked how I would develop the relationship between William Gibson's work and posthumanism, a connection that I begin to describe in the thesis. I had no idea, in that moment, of how I could possibly say anything more than had already been said in the thesis. I could have prepared for this if I'd had the foresight, but it wasn't something I'd contemplated in advance. If this happens to you, do not panic! Help is at hand in the shape of your trusty thesis. Don't be afraid to repeat what you've already done, and any developments you suggest for future research in the conclusion. In the moment it's hard to focus on what you've already achieved in your thesis because you know that the examiners have read it, and you imagine that they don't need to hear you going on about your theories all over again. However, part of the goal of the viva is to check that you wrote your thesis yourself, so repeating yourself is not a crime. It gives you some familiar ground to walk on in a moment of uncertainty while showing the examiners that you really know your stuff.
Good luck to anyone going through this process, I know it's not easy - but it will feel so worth it when you make it through to the other side.