This would appear to be a far more appropriate reason to dial 999 than most. In A&E, if necessary, as you probably know, you could have oxygen. You could have nebulised salbutamol and ipratropium. You could have oral, or IV, steroids. If not improving you could have IV magnesium sulphate, and either a salbutamol infusion or an aminophylline infusion. If, heaven forfend, you actually stopped breathing, they could deal with that.
Or you could stay at home, ignore how sick you are, look for sympathy online, and cross your fingers it doesn't come back worse in an hour.