According to Rajendra Pachauri, who chairs the Intergovernmental Panel on Climate Change (IPCC), meat production puts more greenhouse gases (18% of the total) into the atmosphere than transport. This 18% includes gases released by clearing forested land, making & transporting fertiliser, burning fossil fuels in farm vehicles and "the front and rear end emissions of cattle and sheep" as BBC politely puts it.
So "offset" your meat, rather than your flights, and offset it the real way, by not consuming it!
Which may also help you limit your rear end emissions 