@Anonymous: TIME TO BREAK OUT SOME WELSH COPYPASTA:
Unless you're going to the north and plan to leave a large place and/or student place, you will not need to speak or understand welsh. I've only picked up a few welsh words/phrases, and rarely mix up how to pronounce welsh words I see written down any more (Although it's completely consistent, welsh differs from how to pronounce the same letters in english, most importanly:
"y" is a schwa, unless it's acting line an english "i".
"w" acts like an english "u".
"ll" acts like nothing in english. Put your tongue as though you were making an "l", but instead of vibrating your voicebox, push air out so it flows over the sides of your tongue. If this puffs your cheeks, open your mouth wider (so it makes more of a shape as though you were making an "eeee" noise).
"ch" acts like nothing in english. If you're familiar with the "ch" from scottish, use that. If not, it's not entirely unlike an unvoiced gargle.
"u" acts like an english "i" (so you say "toiledau" like "toil-e-die" ("au" at the end of a word indicates a plural)).
"dd" acts like an english soft "th". ("d" acts like an english "d").
"f" acts like an english "v".
"ff" acts like an english "f".
"si" acts like a german "sch", not quite the english "sh" or "ch".
"i" always acts like an english "ee" sort of sound, never like the "ih" in "hit".
"c" is always hard.
"ŵ" (rare) acts like an english "oo".
). You'll get by without a lick, but if you're interested in learning the language, check out www.SaySomethingInWelsh.com, which is free and pretty neato.

@Anonymous: As for recognising words that are written down, you've got the spaghetti of soft mutation to worry about, but it boils down to "sometimes a different letter flows better than the "real" letter, so use that instead", So in the phrases "Cymru am byth" and "Croeso i Gymru", Cymru (cum-ree) and gymru (gum-ree) are "the same" word, and both mean "Wales".
Reading through soft mutations is a lot easier than knowing the right ones to write, and in listening or speaking you won't even notice.