The standard issue RAF boots should do all you need them to do for the first few months of your career.
Coating them in good thick layers of polish followed by a brisk brushing will help waterproof them, they'll never be 100% but well enough.
I replaced the laces on mine with some that didn't give me blisters on my fingers when putting them on. I also replaced the standard "cheese grater" insoles with some 'double strike' shock absorbers.
As for soaking them, it worked for me. Soak them in the bath, weigh them down so every bit gets covered, then wear them for a day so the wet leather starts shaping to your feet.
The best advice though is to just wear them and keep wearing them until they've broken in and they feel like just another pair of socks when you put them on.
Sadly far too many young people have grown up wearing nothing but trainers all their life. Having soft feet will mean they'll take a pounding when you wear brand new leather boots but ermmm you wanted a job where you have to wear them
Of course I could be wrong and confused my hands with my feet again, so read my words at your own risk!!