1) the ‘a’ is very short and low, heading towards a short ‘o’ in English.
2) both the ‘g’ and the ‘gh’ are pronounced as a softer version of ‘ch’ in Scottish ‘loch’.
3) ‘Vahn Goff’ is completely and utterly wrong. (And if you thought it was ‘Van Go’, I don’t ever want to talk to you again.)