What are you going to miss ? What can't you do ?
Well, for a start, it looks as though you're not going to be able to find the Welsh word for an awful lot of things! Objects, concepts, qualifiers, verbs ....
Here's some strategies you might try ...... DafTesT first ...
◘ You could just make a random guess what the word for, say, "windscreen", might be and try it out and see if they understand. If not, try another guess. After about 3788 tries you might by chance hit on something ½ right and then they could tell you the real word. It could go something like this .. trigtypnawn .... gwrnwrongl .... maentypob .... pluhatgraf.... dihanogog ...
◘ You could get started on writing your own English-to-Welsh dictionary by using the half you have got backwards !
◘ More sensibly, you could make a more useful dictionary by only bothering with the words you might actually need. Still pretty daunting though.
◘ You could make an intelligent guess .. that's an altogether different thing to a random guess . So for "windscreen" , if you knew the word for " car" and the word for "glass" you might use those to get your message across. Or maybe you might know the Welsh words for "wind" and "screen" but the snag there is they might think you want one of those canvas things you put up on the beach.... but they still might get there eventually. This is an important skill.. using what you DO know to make yourself understood.
◘ Another way, maybe a better way, of going about the same thing is to forget about the actual word for a windscreen and just try, using the words you know, to describe what it does, what you use it for, or what it looks like, or where it is. This is much more flexible than the "pulling-apart-the-bits-of-the-word-windscreen " method.That way they might get to understand what you want more quickly, and then they can supply you with the actual word.
◘ It would have been a big help if you had tried "using the words you DO know " to describe stuff regularly and routinely before the drastic disappearance of the other half of your dictionary. Because , in effect, when you are actually trying to take part in a Welsh conversation there's no way that you are going to actually know all the words you would really like to use, and there even less way that you are going to be looking things up every 38 seconds either. So ... do it .. it's refreshingly creative, it's useful, and that can't be bad.
OK ... after all that wordy ( and worthy) stuff, let's refresh ourselves with some Welsh music .... I liked that Wys Gwynedd we saw last time, so here he is again.... with " Fy Nghariad Gwyn" ....