If you are going for a spring gun be aware that they need a very tight regime on loading.

An underlever usually has an inner sleeve that opens up a loading port where you insert the pellet into the breech. I often see people cock the rifle and then let it flop about whislt they shove digits into what is potentially a guilotine.

If the trigger is nudged (say by clothing) or there is a fault with the gun - worn or not correctly adjusted, there is a good chance you will get whacked in the face by a rapidly moving gun and loose or crush fingers in the process.

PLEASE HOLD THIS LEVR AT ALL TIMES WHILST RELOADING and dont close it with the barrel elevated in case of an accidental discharge.

The same applies to a break barrel and a similar failure will result in mashed thumbs, broken nose, re-arranged teeth and a barrel shaped like a banana.

I still recommend joining a club - lots of advice and kit to see and probably try as well as the joy of shooting.

Also, an experienced shooter can show you the ropes while you get up to speed sufficiently to squeeze a shot off at a pulse.

Suggest you also consider what your reaction will be if you miss/wound and practice a swift back up shot. This is NOT as easy as it sounds when in a live situation - people tend to flap and loose it when in practice they might have been fine.

Then there is the potential for upset from the shooter.
I hope you enjoy your shooting when you get started