I didn't have it at Pembury but in Yorkshire by the surgeon who pioneered this treatment. The peritoneum is a very thin membrane that lines the pelvic cavity and goes round all the organs. Funnily enough my son is in London at vet school and last week he was telling me about a horse they dissected and he was fascinated by the peritoneum and how it was so thin they could see through it. It made me think of how difficult it would be to excise spots of endo from something so thin as it would just end up full of holes. When you have extensive endo the peritoneum is likely to be covered, so total excision gets rid of all endo on it in one go whether it's visible or microscopic and then means all the organs can be accessed to excise endo from them too. The peritoneum grows back.
I had stage 4 and my surgery lasted 6 hours with total peritoneal excision, extensive adhesiolysis, separation of bowel from the pelvic wall, shaving of bladder and both ureters. I had no uterus or ovaries as they were removed years previously. I was private so only stayed in two nights. That meant coming home with a catheter and bag but it was no problem and I lived on my own with a son to look after. I arranged for the district nurse to come and do the necessary. I had a little puss come out of one of the puncture holes for a while but it soon cleared up with a course of antibiotics. Just be careful to keep the dressings dry. I made the mistake of having showers as the dressings were waterproof but I think they must have got damp. Apart from the expected soreness inside for perhaps a couple of weeks I was pain free after having to crawl to the loo in agony prior to surgery. Take the recommended pain killers for as long as recommended and you'll be fine. Six years on I am still pain free. My specialist does follow ups so I've had two questionnaires send to fill in. Every one is different obviously but you will be having the most thorough job it's possible to have for endo, so the future should look good for you.
Prior to surgery you'll have to drink pretty vile stuff to empty your bowel so be prepared to pebble dash their loo! They went through everything with me afterwards and sent my GP/nurse aftercare instructions. But ask them to run through it all with you too - when the dressings need taking off, how long the catheter has to stay in etc. If I were you I'd keep out of the shower as long as you can and just wash your bits for a while to keep the dressings dry as long as possible.
All the best x