It is understandable - apart from a couple of ambiguities, but a little odd and not natural sounding. "Hi, I bet you are somewhere outside this city to say the least !! - if you mean that you are guessing your friend is away on a trip somewhere (you don't know where), then just say, I bet you are away at the moment. 'Outside the city' is very peculiar and I am not sure what the 'at the least' is meant to convey? You are surely arranging your Xtmas trip. Do you mean you must be busy arranging it right now? or that your friend will already have arranged it? Where are you travelling this year? I assume this question refers to the planned Xmas trip, as the year is nearly over? Would you like to come over before your days off? This is very odd. If your friend works, she can only come to visit you on her 'days off'. So not sure how she will do it 'before' her days off. Do you mean, would you like to come and visit before you head off on your trip? We can have a vegan meal together" Here is one alternative. Hi - I bet you are off somewhere at the moment on your travels again. You must be arranging (have arranged) your Xmas trip by now? Where are you going this year? Would you like to come over for a vegan meal before you head off?"

It sounds a little odd to me. Why would they be outside the city? I guess you might say it if they were (say) camping, and there were no campgrounds in the city itself. Or are you referring to them being away from their home city? Did you ask "where are you?" before that? You have a typo in Xmas. The 'you are surely' sentence is also a little odd. I would at least add 'already' to make it less insistent. I would say "I guess you are already organising your xmas trip"

Looks ok to me