I've learned a trick to spelling and pronunciation in Celtic languages:

The letters look the same as in English but have different values sometimes. If you can figure out what those letters are how they're pronounced, you've got a start.

For example, in Cymraeg or Welsh, an 'f' is pronounced as an English 'v'. Ff is pronounced as an English 'f'. D is pronounced the same as in English but dd is pronounced 'th'.
So, Caernarfon (a town in n. Wales) is pronounced Care-nar-Von. Yr Wyddfa (Snowden peak) is pronounced Ear-with-va.

In a similar fashion in Gaelic bh is pronounced v so Siobhan (a given name) is pronounced Sho-vaughn. I tried to name my daughter Siobhan but was overuled by my wife. <sigh>

The following is English then the same thing but written in the Welsh alphabet. Very illustrative.

Good luck: I hope that you can read this, and that it makes sense to you. If you can read this, then you are doing fine and will have no problems at all in learning our fine Welsh alphabet.

Gwd lwc. Ai hop ddat yw can ryd ddys and ddat yt meiks sens tw yw. Iff yw can ryd ddys, dden yw ar dwing ffaen and wil haf no problems at ol yn lyrnyng awr ffaen Welsh alffabet.