1997 Ford Fiesta petrol smell around filler cap

I understand this problem is from the breather pipe below filler hole possibly. Common in fiestas can you tell me if it is dangerouse or just more anoying. Its worse it hot weather finances are not good so is it expensive job.I also believe it could be from I fitting in the tank sometimes its worse when you have just started the car up. Car had to be repaired recently following a bump in the corner of back bumper.I have asked them if they disconected or removed anything around there as it never used to do this. They have not been helpful I changed filler cap as it was a poor one on there but still no luck stopping it many thanks sue smith