The guide is all about healthy food preparation. The only thing I got from a tuckshop was bad teeth.

Guía de Nutrición e Higiene para Kioskos Escolares
issuu.com/nicaragua.../gu_a_nutricion_e_higiene - Translate this page
18 Mar 2009 – GuÃa de Nutrición e Higiene para Kioscos Escolares Ministerio de Educación Programa Integral de Nutrición Escolar PINE-MINED ...

("School snack bars/kiosks" in the plural, of course.)

I've had a look at the links too. It's not a canteen or dining room, which implies a large place with tables and a kitchen attached, serving lunches. I think "tuck shop" is (a) old-fashioned (and, as has been said, associated with British boarding-schools and Billy Bunter) and (b) very UK and Commonwealth, and not used in American English, and (c) very small, normally just a shop selling comestibles, whereas here there is apparently space behind the counter where they prepare food, wash up, and so on. Also, "tuck shops" used to sell a lot of sweets and pies and stuff like that, and don't have the healthy connotations they are talking about here.

The word "kiosk" is actually used for this, though again mainly in the UK, I think. But "snack bar" is a more common term, and widely used in the US as well. These "kioskos", like most snack bars, sell food and drink but not full-scale meals; the one on the cover has a couple of bar stools where you can consume your purchases, or you can take them away. Snack bars can be larger, more like cafeterias, with tables, serving light meals at lunch time, but I think it's the best fit, along with "kiosks".

"School Snack Bar
Working with local authorities, schools and colleges, Blackburn Trailers have designed and built many different types of kiosks and semi permanent structures for all types of on campus requirements. These range from very small tuck shops to sectional internal serving walk through hot snack units.
The kiosk you see pictured here is a small snack bar positioned next to a covered walkway. "
http://www.kompak.co.uk/kiosks/school-snack-bar/

If you look at the picture, it's very much like the "kioskos". Here's an American reference:

"Four teen boys were caught with their hands in the cookie jar when they broke into a high school snack bar Wednesday.
[...]
The snack bar is actually a converted storage shed, a small outbuilding near the baseball field."
http://www.the-signal.com/archives/3364/

This again sounds like just the same sort of thing.

Several terms (including those already offered) are correct, it all depends on context and the register you need.
Perhaps looking at Google images for each term can help you decide.

History of Amigos
www.amigosforchrist.org/about us/history.htm
In Nicaragua, they witnessed starving children scavenging the city dump for food, ... by raising money for a local school cafeteria through a series of fundraisers.

The results of a collaboration
www.intervida.org/en/collaborate/csr.../the-results-of-a-co...
14 Feb 2012 – El Salvador; Guatemala; Nicaragua ... The school buildings, which include 3 classrooms, a school canteen, accommodation for the teachers ...

Malbank School and Sixth Form: School Canteen
www.malbank.com/school_canteen.html
The Malbank School Canteen: information and example menus. ... www.myschoollunch.co.uk. This website provides a wide range of information about school ...

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Note added at 1 hr (2012-05-10 16:11:41 GMT)
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Google search with each of the terms (school tuckshops/dining rooms/lunchrooms/cafeterias/canteens) + Nicaragua shows CAFETERIAS to be the most common by far.

used to be the typical term, but I'm not sure if it would be appropriate in this context (images of Billy Bunter...)

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Note added at 7 mins (2012-05-10 15:03:38 GMT)
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*School meals service* may be another possibility, depending on what the document is actually referring to by "Kiosco Escolar"

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Note added at 25 mins (2012-05-10 15:22:04 GMT)
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Hi Manuel, yes, looking at the links you gave, I think tuckshop would be appropriate here, despite Billy Bunter associations :)

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Note added at 1 hr (2012-05-10 16:12:43 GMT)
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An example:

"As part of the UK government's recent promotion of *healthy eating* as part of healthy lifestyle, the role of *tuck shops* in schools has come under increasing scrutiny."

from http://en.wikipedia.org/wiki/Tuck_shop

So Wiki spells it "tuck shop" (i.e., with a space in the middle).

Also, although it is a basically UK term, as Neil pointed out, it seems to be used wherever the British have been, although in the USA it seems mainly to be used as a retro/nostalgic name for restaurants.