Welsh has no dipthongs. So no Y in cake. Which is why a lot of the Clofftafodau mistake the Welsh accent for Geordie.
The other rules are mainly alphabetical.
No V - sub 'f' as in 'Felin' or voice.
F = ff as in Ffairfach or fornicate.
No K, all 'k' sounds are covered by 'c'. S really means s.
You can't pronounce the 'ch' if you are too posh to clear your throat in public. Bwlch-y-Gwynt.
'Y' on its own is generally '..uuh' alongside a 'w' it is an 'i' sound as in wind. Or Gwynt.
And the big one. 'Ll'. The big double 'Ell.
To pronounce this, first say 'l' as in 'Lady'. You are vocalising the 'L'. Your voice box is turned on. Now say it again, but turn off your voice box and just exhale WITH YOUR TONGUE IN THE SAME PLACE.
Llanelli, Llandridrindod, Gelli-Aur etc.
Oh yes. 'u' is an'ee' sound most of the time. So Aur (gold) is Ai-eer (fast). And the R is hit on the beat.