After setup costs I expect income in the first year to be zero or negative. Second year I expect income probably would cover travel expenses but if it did little left over for anything else. Path beyond that is tricky to predict. WMDE has certain advantages (such as the language barrier) that WMUK will not.
That's an extremely pessimistic outlook. Why are you bothering to take part if that's what you think? If we can't make any money in the first year, how will we make it in future years? And if we're not making any money, what's the point in having a chapter? We won't be able to do anything we couldn't do now.