So, up till now I've been trying to model my pronunciation after Munster Irish, but I'm a little worried because (although I'm stoked to be in a 'scoil Ghaeilge' anywhere!) my teacher is a Connacht speaker from Spiddal in Galway, so she might unknowingly correct something of mine which is perfectly fine in Munster (like final '-adh' in a word like 'seoladh' pronounced as /av/ and not /u/), but not her dialect.

Any thoughts?

Yes. Don't worry about it! If you're constantly filtering everything she says for dialect, you'll get far less benefit from the instruction. I know because I've been there, first as an Ulster learner with a Connemara teacher, and then later on as a Connemara learner with a Munster teacher. In both cases I started out by second-guessing everything the teacher said, trying to make sure I didn't 'corrupt' the bit of Irish I had, and in both cases I noticed that my Irish - my rate of progress in Irish - made leaps and bounds as soon as I gave that up and just settled in to listen.

If something seems strange or at odds with what you think you know, make a note of it and look it up later; otherwise just absorb and imitate, and don't worry that you may be mixing things. You almost certainly will be, no matter how hard you try, and that's OK. Go on a Munster reading/listening jag when you get back, and they'll sort themselves out soon enough. Even if they don't, it's no shame to have a mixture either, and no native speaker in the world will hold it against you. Think about it. Your English reflects a combination of outside influences (parents, community, teachers) and probably a few personal choices as well. Why shouldn't your Irish! Amhlaoibh Ó Súilleabháin is a classic example of this.

When I started learning (still in the beginner stage!) I thought I'd dive right into a particular regional dialect and go from there. I soon realised that it would be too much, too soon. My main learning aid is based on the so-called official standard with a strong Conamara bias in terms of pronunciation.

I too wouldn't worry about mixing up dialects at this point, but consider focusing in on Conamara Irish as you progress. The number of habitual Munster Irish speakers in the Gaeltacht is barely 3,000 so you will more than likely encounter speakers of the other dialects who won't pronounce words in the same way as you've been taught, thus hindering communication somewhat. Some may say: "Big deal!" but as learners, it's something we shouldn't underestimate. Conamara Irish has over five times the number of speakers, for example.

Just my 2c.

I've been speaking Ulster Irish from the beginning ; I had teachers from Connemara and Munster but I didn't change anything in my Irish. Just tell your teacher that you want to speak Munster Irish and if she's nice, there'll be no problem.