I passed my test yesterday and I have never been so relieved! I found the whole process very difficult.
Here's my experience for what it's worth:
I've driven a manual in the US for the past 30 years but they are so strict here that I knew I would need lessons. My test was in Aylesbury (Oxfordshire) and involved driving through a triple roundabout full of zebra crossings and navigating a gyratory among other things. I passed the first time with only one minor which even shocked my instructor.
It may sound crazy but I verbalized what I was doing throughout the test and it helped me to focus and not panic. I told the examiner at the beginning not to worry if I talked to myself and he laughed and said "it's okay, it's not a test of your sanity"
I literally verbalized every time I was checking my mirrors, watching for pedestrians, moving to the left, signalling, etc.
I took 20 hours of lessons in order to fully understand what they are looking for on the test. Although I initially resented it and hated to spend the money, I ended up learning a lot and I think I'm a better driver as a result. I even prepared by printing roundabout maps and studying them because Aylesbury has some really crazy roundabouts that grow extra lanes as you go around-very weird. The instructor also reviewed lots of very tricky areas that would have caused me to fail if I had not known about them (one way systems for example).
I found the theory test and the driving test very stressful and I wish I had started the process much earlier because I never dreamed it would take almost a full year. If you are still going through this process I definitely recommend taking lessons. Learning to drive in the UK has definitely been the hardest part of the adjusting to the culture for me.
I often read these forums and also want to thank everyone who has shared their experiences here. It helps so much to know that I am not alone in how I feel!