Just a little update: I passed my (automatic) test!
I did find the test to be fairly easy in the end. Although I was definitely criticising myself heavily in my head throughout the whole exam ("You totally went 2 mph over the speed limit there," "That could've been better," "Did I stop long enough before that weird box junction?" etc).
As we headed out from the test centre the examiner said he would ask me to perform an emergency stop at some point, but that never ended up happening and I wasn't going to remind him.
I drove along with a SatNav for about 25 minutes. The examiner would occasionally ask me to pull over to the left when it was safe and then move on again when I was ready -- that happened about 3-4 times. My route did not include any of the major roundabouts in the area, luckily. We were on country/village roads for the most part. After the SatNav route finished the examiner just verbally directed me for the rest of the test with plenty of advance notice for each turn. I was instructed to reverse into a parking bay at the test centre at the conclusion of the exam. I was asked about what ideal tire conditions are (no gashes/punctures, 1.6mm tread) and to demonstrate how to wash my rear windscreen while I was driving.
The only fault the examiner mentioned is that I tend to signal>>mirror>>mirror rather than mirror>>signal>>mirror.
As for costs...
I took three 2-hour lessons @ £56 a pop. Then the use of my instructor's car on the day of the test was another £56. So, £224 (lessons) + £62 (practical test fee) + £23 (theory test fee) = £309 total spent on getting my UK licence in order.
Thanks for the advice from everyone here. And good luck to all those getting ready for their tests