Thanks for all your help MrsM, Mama, Iwish, Ilove, TAFKA, Lion, Sidge, GwarchodwrPlant, lowrib, rokersmum, Frizbe, bronze, Flame, Jas, migola, Dysgu, skybright, Ninjacat, llareggub, Rachie, doesmybumlook, boodleboot, seaturtle, foreverchanges, Dee, Joycey, salvadory, BlueChampagne and Tummum.
Feeling much happier about using a Welsh name in England now. Lowrib - I loved your rant post, so true - it wasn't so much the spelling/pronunciation that I was worried about but more potential teasing for a boy. I agree that if you read the naming advice on baby name sites everyone would be called Tom and Emma.
Am definitely tending towards Aneirin/Neirin for a boy now (thanks Ilove) and seems to be well received by people. Also like that it probably means either honourable or golden. I like the Aneurin spelling because of Bevan but don't like the closeness to the word aneurysm (now I am worrying about pronunciation ).
Still unsure for a girl, tending towards the snow-related meanings esp for January baby. Like the way Eirlys looks and love the snowdrop meaning but confused about pronunciation - drawback of growing up in Gwent and only doing one year of Welsh at school. I find the r before the l difficult. Any Welsh speakers who can tell me how it should be pronounced?