My name is Gwenllian and although it's nice to have a unique name, I want a name that's easy to pronounce. I can't tell you how many times I've had to spell out my name in Starbucks and to end up with a name like 'grunphin' written across my drink! I have yet to come across a non-welsh speaker who can pronounce my name correctly. I think you have to be a welsh speaker because we have a different alphabet with letters like dd, ch, ll, ph which are hard to pronounce.If you really are desperate to pronounce the 'll' correctly then I would go on Youtube.
Its definitely not pronounced as described above, sorry. 'Ll' is a single letter, which is very hard to explain the pronunciation of, but it does not sound like the letter 'L'. I know a couple of Gwenllians, and I don't know a single English speaker who can pronounce the name properly!