You could read an old Scottish Gaelic book, like eg. Dùn-àluinn by Iain MacCormaic, it’s apparently written in fairly authentic dialectal Mull Gaelic (the author was a native speaker). Or you could read through Popular Tales of the West Highlands – collection of folk tales collected from numerous 19th century speakers (there are 4 volumes of this, and you’ll find both English and Gaelic in the books, you can find the other volumes on archive.org).

There are also recordings on Tobar an Dualchais.

BTW, in Sc. Gaelic you say is urrain dhomh (…) a tuigsinn with the possessive (‘her understanding’ = ‘to understand her’), the i a thuigsinn form AFAIK is not used (you’ll find this kind of structure with the meaning ‘(eg. I want) her to understand…’ though).

There is a Gaelic forum with lots of resources, and some of the participants are native speakers or more or less fluent:
https://www.foramnagaidhlig.net/

I have heard some beginning learners say they do not always feel welcome there, but I'm (way) far from fluent and have usually found the participants to be friendly and helpful.

The Gaellc college on the Isle of Skye. Sabhal Mòr Ostaig, has in-person classes and courses and links to online resources and distance learning resources:
https://www.smo.uhi.ac.uk/?lang=en

Within their site is a page with links to lots of online info:
https://www3.smo.uhi.ac.uk/gaidhlig/english.html

There is also an American Gaelic society, An Comunn Gàidhealach Ameireaganach, which has info re courses and resources in the US:
https://acgamerica.org/

There are also several online sites for learning Gaelic, such as this one, Learn Gaelic:
https://www.learngaelic.net/

That should get you started for now. 3d Trcek I'm a moderator here, so I'm also going to copy this thread to the Gaelic part of this forum, which you may not have noticed. There are a number of threads there which might be of interest to you. https://eldfall-chronicles.com/product/single-model-kitsune-spellmaiden/