AFAIK, Hangar Uno is pretty overpriced for Argentinean terms and from the feedback of some 'natives' not as great customer service. They do helicopters as well.
When talking about San Fernando, I'd probably go for
Flight Center, C152, PA-28 which should be cheaper. FC also have some choppers.
There's also
Aerodot that should be cheaper than Hangar Uno. Rudder Corp think is tad pricey, Delta Charlie changed ownership or doesn't have aircraft for the minute, something of that kind.
If you want even cheaper rates for various taildraggers, Cessnas, etc, go for
Aeroclub Dalale, Miguel Angel Mozzone (4282-6163/ cel: 1561891827, one or two planes, haven't found MM's website), or
Rafael Lupetti - that one's good. Also 'Alas del Sur'. All based at San Justo, 45min train ride from BsAs downtown. You can stay overnight at their basic housing, if you plan flying weekend.
SanFer is towered tarmac, but most places are grass. Moron is bit further, tarmac, can't tell schools off the top of my head.
Without speaking Spanish and doing 'convalidacion' I'm not sure about renting/hiring for solo. Flight Center should let you know more. Not a problem with instructor as safety pilot.
FC have interactive map for some smaller and bigger XC flights around Argentina. Plenty of place to fly to from BsAs.
As for gliders, you can hitch a trial lesson - 'bautismo', but don't expect renting it yourself just like that, even with some gliding experience (not sure you have). BTW it's gliding comp season over there now so not all instructors may be available. Gliding is very club environment.
Also be aware of the limitations of grass runways after heavier rain.
There are some vids, def. from Flight Center and bunch of other clubs on YouTube, to get an idea abou the airport.
If you speak Spanish, check out
http://www.aeroforo.com for some aviation talk, Arg centered.
As mentioned, Argentinean CAA is called 'Fuerza Aerea Argentina' and the civvy side is dealt with by CRA department. Yes, not too fast dealing with them I was told.
That should speed up your research. Have fun in Baires. I'll try to get over for couple months flying out in July.