This is a good starting point. Some fun notes on Scottish traditions specifically.
Is a good general source.
I also highly recommend purchasing:
https://www.amazon.com/Carmina-Gadelica-Incantations-Alexander-Carmichael/dp/0863155200
It's a great resource that you will turn back to a lot. On the surface level, there are a lot of things that can easily be "paganized". On a deeper level, it records folk practices that give hints to older practices.
Offering to the Gods, ancestors and spirits is a very good way to build that sense of connection. Simple offerings of oats, cream, butter, and honey are a good start. If you are poetically inclined, you could compose poetry to accompany your offerings, otherwise a simple prayer will suffice.
Since your leaning into your ancestry, you could say something like:
"Hail to the Gods my ancestors swore by, With a grateful heart I leave these offerings for you. Remember us who remember you".
Good luck on your journey!
Ronald Hutton's Pagan Britain is well worth a read a read as a primer. Hutton covers a lot of material from Ireland as some of the best preserved evidence of insular pre-Christian ritual practice is there (pre-Celtic practice as well)
The sources are in folklore collected in the 19th and 20th centuries. One very good resource for these stories is The People of the Sea by David Thomson. It's an easy book to get, looks like only a couple of dollars on Kindle. https://www.amazon.com/People-Sea-Celtic-Seal-Folk-Canons/dp/1786892464/ref=sr_1_1?crid=MIY992ZHRW5L&keywords=the+people+of+the+sea+david+thomson&qid=1648942799&s=books&sprefix=the+people+of+the+sea+davthomson%2Cstripbooks%2C613&sr=1-1
I’m just starting to learn too! This book has short versions of some of the stories from the Mabinogion but also some ideas to start deepening your connection to the deities https://www.amazon.co.uk/Pagan-Portals-Goddesses-practical-introduction/dp/1785356216/ref=mp_s_a_1_1?crid=1S2DK2ZPZFE0D&keywords=welsh+gods&qid=1644248139&sprefix=welsh+gods%2Caps%2C73&sr=8-1
Take heart, friend! :D
It's likely that I don't know much more Gaelic than you do, but if one considers the vast vocabularies of any other discipline, be it music, computers, or even a beloved story universe, it is going to take a frustrating amount of time to wrap one's head around the in-group terminologies. I know this is an obvious sentiment, but I nonetheless think that it helps to state it plainly; it takes time.
One of the aspects I have come to love about our pagan path is that there are no shortcuts to attaining the sacred knowledge of our ancestors. We cannot even be certain that our knowledge now directly matches the experiences and teachings of the ancient Celts from any single place or point in history, but therein lies a humbling lesson against certainty, I believe.
The Gods speak language beyond language and it's us who are limited by tongues. They draw us to the aloofness of nature, away from the certainty of wrote doctrines. What we share is a beckoning to those raw aspects of our culture much the same as our ancestors and that expression manifests in our homes, artistic expression, and service to the land and people.
But enough of my preaching! You got the attention of /u/Norse-Gael-Heathen, who is a humble, but incredibly venerable leader on these matters and I think his advice is superlative: approach pronunciation with your wit and as you learn more, so too will your inner-monologue evolve. Your doubt and concern are merely the evidence that you care.
While it is not as encompassing as other sources, the learngaelic.scot dictionary aims to have a recording of every word and phrase that it contains. I can also recommend the small Gaelic-English Dictionary by Geddes and Grosset, which contains IPA pronunciation keys.
Keep up the great work and hello from the Portland-metro area!
I've been really enjoying Lora's guided journeys personally but I get that they won't suit everyone. Therean alternative method based on the Immrama (I haven't tried it yet but have been recommended by several Irish Pagans) I'm going to link to the book on amazon for the method, not sure if the author has audio recordings or not but it might be a start
https://www.amazon.co.uk/Imramma-Eblanna-Raven-ebook/dp/B01ELIHBRQ
I'm a big fan of Irish Paganism: Reconstructing Irish Polytheism by Morgan Daimler. It's an excellent beginner's book that conveys the basics and lays a foundation. I'm very grateful it was written. The author also takes a rather academic approach, focusing on what's been verified through historical documentation.