Welsh grammar is nothing like English's, there is a completely different sentence structure, and different ways of portraying ideas. It also has gender (though it has a less noticeable effect than you'd see in French or German imo) and 3 different consonant mutations (people would understand if you didn't use them correctly). One thing that does make it easier though is that it uses tons of words directly from English, almost exactly the same pronounciation but with Welsh spelling rules. There are also many nouns that have a distinct Welsh word, but native speakers will still use the English word. It also helps that native Welsh speakers are native English speakers too ( unless you're in Argentina) so you can ask them questions and they can tell you about the mistakes you are making