The UK has a green wheelie bin used to pick up garbage.
A typical bin bag weighs about 3 kg. It is reasonable to assume that there are 6 or 7 garbage bags in the bin.
Or, 20 kg per week.
There are 66 million people in the country.
Let's say 22 million households with a wheelie bin have their garbage collected each week, and about 50 weeks in a year.
Therefore a guesstimate can be
2 * 10^1 kg / week * 2 * 10^7 * 5 * 10^1 week/year
Or, 2 * 10^10 kg/year
The official figure stands at about 3.1 × 10^10 kg/year