Back in the day, nobody negotiated on a new car. That was the price, that was what you paid. Dealers now expect people to try to negotiate, but still some Brits think that it is somehow rude or grubby to do so.
When a dealer asks me "Ho much are you looking to spend"? I always say "Nothing at all, that is where we can start" it then goes from there, haggle them to the bone because they will always make something from it. If you cannot get cash off, get accessories, if on finance demand half of their commission from the finance company, mats, full tank.
I got three years of GAP+ insurance worth £700 on mine when I took out finance.
Let them know you are a serious player, not a time waster. They will respect that and chase you for the money. Stick to your guns, you will know instinctively when you hit a dead end with them.