Good luck with the new career.
Drains, and the stuff in them, can be fun and interesting. I've done a lot of drain work in and around my house and though being up to my arm pit in poo was unpleasant the overall 'getting the drains working right' and repairing broken sections was quite fun.
TBH I'm pretty nervous, especially now I've got a copy of the LGV Theory Test to learn

.
It's not too bad. I did my C+E a while ago*. The most awkward bit of theory is around the tachograph and drivers working hours.
The scariest thing was the emergency stop. I thought the whole cab was going to tip up and the sleeping bunk was going to hit me on the back of the head!
*I don't have my licence as my test was rendered void when I 'sacked' the examiner for not knowing the law and asking me to carry out an illegal maneuver on my test. The examiner tried to fail me but DVLA suspended the examiner, and his supervisor, for retraining instead. I never did get around to retaking it.