We are currently staying at UK and in the area where I am the only Shia. I am here with my office friends who are Kafir and my neighbours. Occasionally they send food cooked by themselves. We are dumping or just throwing them in bin as we can’t bury it. Is it any other way of utilising the food or it is fine if we keep dumping this way. As it is also food from Allah(swt).

You may give such food to the poor but if you don’t know about the food that it was touched by kafir or not then you can use it.
Please follow the Fatwa of Ayatullah Sistani in this concern as mentioned below:

1Question: Is it permissible to eat foods prepared by Christians and Jews?
Answer: Since the followers of the past revealed religions (that is, the Jews, the Christians and the Zoroastrians) are ritually pure, many of the problems concerning the status and permissibility of the food are resolved when we live in their midst. It becomes permissible for us as Muslims to eat from their food no matter whether they touched it with their wet hands or not as long as we do not know or are not sure that it consists of what is forbidden to us, like intoxicating drinks.

2Question: Is it permissible permissible to eat from non Ahlul Kitãb people?
Answer: A Muslim is allowed to eat the food prepared by a non-Muslim who is not from Ahlul Kitãb [for example, a Hindu or a Buddhist], provided that he does not know or is not sure that the non-Muslim touched the food with wetness; and provided that he does not know or is not sure that the food consists of what is forbidden to him like intoxicating drinks. As for meat, fat and their extracts, the food cooked by non-Muslims should not contain any of these. If the food contains meat and animal fat, he should be sure that they are halal .