What is this "servicing" of which some speak?
In the last 45 years of bike ownership I can't remember taking a bike to a shop for anything.
Currently I have 5 bikes, all self maintained, and I am no mechanical expert. Bikes are generally simple machines. Keep on top of general maintenance and a bike shouldn't need servicing.
The only exception to that might be the chain as worn chains result in early demise of cassette, so check it regularly with a measuring tool (google) and replace when necessary.
Specific bike tools:- I have said chain wear measure, chain splitter, crank pullers, cable cutters, spoke key, and a torque wrench (and only bother with that on the carbon framed bike).
Keep on top of on-going maintenance like gear adjustment (simple adjustment of cable tension via barrel at rear derailleur); keep brakes properly adjusted and aligned; keep wheels true (spoke tension); lubricate moving parts and cables, and keep fasteners tight. Replace bits as and when needed (the only wear out parts are chain, cassette, brake pads, tyres, bottom bracket; all of which last thousands of miles - chains are thinner the more gears you have so wear quicker, I got 2300 out of chain on 11 speed cassette, but double that on 9 speed) .
Replacing parts is not complicated at all, with the right tools. YouTube is your friend!