I would be interested to hear from people who have participated in the opposite Bootcamp from the course that they have been studying. What did you do to prepare? What worked well, or what do you wish you had done?
I am very much looking forward to the Bootcamp this September!
Bronwyn
Shwmae Bronwyn.
As a former bootcamper at Tresaith who completed the Southern course, I couldn’t really tell you how the experience was from a northern course students perspective. I was there with a few bootcampers who was doing the northern course, but not once struggled on bootcamp.
You see, there are very few differences between the 2 dialects, and they’re mainly just the odd word or two - but the differences are focused on in these courses which may give the learner a kind of false sense of separation, when in fact, it is very much the same language and the differences are really small. In any case, you pick up the differences rather quickly and understand that it’s there and that’s how they say it and that it means how you say it. An example, you might hear your friend say “llaeth”, so you know they mean “llefrith”. It becomes second nature after a while. Besides, in that part of Wales, both dialects are normally heard anyway.
So, basically, the advice here is don’t worry!
In any case, you may have another northern learner or 2 there as well. But when you do go, it’ll be an unforgettable experience, not to mention rewarding, and I’ve no doubt in my mind that you will enjoy it.
I don’t think there’s been a single Bootcamp yet where all the participants have been following the same version of the course - and it’s never been a significant problem - just adds to the richness of the week 
Helo Bronwyn
I did the northern course and went to the Tresaith bootcamp last September. There’s no need to worry. I didn’t really do any extra preparation other than listen to one of the southern lessons (unless you also count watching a few episodes of Pobol y Cwm!). There’s not that much difference really, as faithless78 says it’s really just a few words. I was able to understand everyone perfectly well. I’m sure you will find there are other learners at the bootcamp who have studied the northern course - there were I think three of us last September?
My advice is also to just relax and enjoy it! I certainly enjoyed it and would love to attend again, hopefully next year.
Pob hwyl!
I didn’t really do anything special to prepare. I wish I had done a lot more listening to Welsh (of any kind) in the weeks leading up to them ( two so far), but that wasn’t really a specific north-south thing.
As others have said: it’s not really a problem, and there will probably be other northern learners there as well. Nevertheless, the wrong 
“opposite” dialect/accent does take a little getting used to.
Some things that threw me at first were:
“wi’n siwr” instead of “dw i’n siwr”
“sai’n gwbod” instead of “dwi ddim yn gwbod”
“bita” instead of “bwyta”
“cwpla” instead of “gorffen”.
…and probably a few others, but the ones above stick in my mind.
Grêt! Byddi di’n cael llawer o hwyl. 
Please go for it. Yes, there are some differences but my experience w as that it added to the joy of the week. We were split pretty evenly. We had no problems with understanding. It helped me to realise the differences were really only akin to e.g. North East English v West Country accents. The only difference is that Welsh seems to have different written forms as well as different words/accents. Plem
PS. I tried to do extra prep for Bootcamp. It stressed me out and disrupted my learning routine. My advice would be to carry on with you learning routine and enjoy…