I sympathise with you, they really are nasty things. My doc prescribes Adcortyl in Orabase paste, I've noticed you can now buy it without prescription. It's a yucky paste but might help to clear them up over the weekend until you can see a doctor.
To keep them at bay I use Gengigel anti-bacterial mouthwash - you can get it in Boots and it's not cheap but I find rinsing with a small amount every other day helps.
The other thing a doctor can prescribe is Corlan pellets, they are small steroid tablets which I use as a last resort and work for me really fast but the taste is
Hope that helps and you get some relief soon,