Working in a mixed environment

I have been offered a job as a mail sorter with a postal company. I will simply order and arrange post, letter and parcels and check the postage has been paid. But some women work there although they work in a different section so I would not have to look of mix with them at all, they also play music in the background. Is this a halaal job? Please note that I live in the UK and most jobs here contain some haram things like alcohol, haram foods, haram clothes, gambling, riba, free mixing, Christmas, easter gifts cards and presents. I am very poor so I can't do hijrah to a Muslim country and my mother is forcing me to do this job as we are in need.