"Bob is from England."
Translation:بوب مِن إِنْجِلْتِرا.
Both can be correct but the g pronounciation is far more common because it's a loan word related to "anglo" and "terra". It's normally pronounced as g, and can be written with a kaf or even qaf in places where qaf is pronojnced as g.
The letter baa can also be pronounced as p in loan words.
And sometimes و makes more of an "oh", "o", or "ah" sound rather than "uu" or "au" in words like Bob and Coca-Cola, and ي can make more of an "eh" or "ey" sound rather than "ee" and "ai", but those sounds are already native to many dialects, in words like yom = day, and beyt = house
For vowels, yes there are some fairly consistent rules. For consonants, it varies by dialect, not by strict rules.
The letters that seem to vary most are ج and ق.
The letter ج is normally pronounced like a j, as in "edge" and "jelly", but in Egypt most of the time it's pronounced like a g, as in "girl". In urban Levantine dialects it tends to be a softer zh type sound, like in "garage" or "azure" or the French pronoun "je".
The letter ق is often pronounced like the letter ء, as a glottal stop, as in "uh-oh", or as a g pronounced in the back of the throat. This is common in the Levant well as Egypt. A common phrase that uses this is بالحقيقة "bil-Haqiiqa" meaning "in reality". Normally I've heard it pronounced "bil-Ha'ii'a". And other dialects, especially rural dialects, ق can even be pronounced as a k/ك.
Many dialects have also lost the distinction between ت and ث, so both are pronounced like ت, as well as between د and ذ, where ذ can be pronounced as a d or z rather than like the th in "the".
For vowels it's a little bit more straightforward. a and i and u are pronounced as in "bet" and "beet" and "boot" respectively, unless they are next to one of the "emphatic" consonants ح ر ص ض ط ظ ع غ and ق. In that case the vowels a and i and u are more like the vowels in "cod" and "kid" and "could" respectively. For more on this vowel contrast Google "imāla". But remember that in words and dialects where ق is pronounced as a ء, the nearby vowels are pronounced like usual, without imala, as in "bet" and "beet" and "boot".
Other than that, and the exceptions made for foreign loan words, Arabic is mostly phonetic, meaning each letter corresponds to one particular sound.
Still, your best bet is to listen to a native of your target dialect pronounce words you might not be sure about.