Hey NCOT...this burning issue is my major complaint. Will tell you the things I have found if they help...some already suggested.
Get a hand held shower sprayer (like the squirt bottle theory only more relaxing!). I use it whenever it is possible to jump in the shower right after going. I wipe as little as possible--even baby wipes were to rough on my tushy when I was where you are in pain.
I tried vasoline, all sorts of diaper rash ointments, Calmoseptine, olive oil, salts and Neosporin. The vasoline, Calmoseptine and diaper ointments were helpful, but they clung to my skin and held on to some yucky stuff---then I had to wipe more and boom more pain---now you want to talk TMI! The neosporin had a pain relief ointment that was a god send at times. My most recent colo-rectal guy told me to get an over the counter Cortizone cream. I found one with aloe so I tried it----loving it and it doesn't linger on the skin.
Get a sitz bath! Assuming they have those in England too. plastic tub that fits over the potty and has what looks like an IV bag to add warm water to it. I would soak as long as I could and it relieved both the burning and the muscle strain.
Try a saline solution for contact wearers on the tushy. It seemed to help a lot. I would put it on the TP if I had to wipe and it stopped some of the hurt better than using baby wipes. I have also squirted it on the area and found it soothing.
Hope you have some relief.