Halal food made in a place with haraam food

I work in London and sometimes when I go lunch I can only eat fish or halal or vegetarian now places which sell these items recently the question came in my mind where are they peparing these sandwiches salads meals.
My question is
1. If a place cooks in a cooker or oven pork and later they cook beans in the same pot after washing or same oven can I consume this
2. If sandwiches are made next to chicken which is not halal or other non halal meat can the egg/tuna sandwiches be consumed not knowing if they are made in same place or not