I was also going to suggest clove oil. You can get it from Boots, Superdrug or other chemists - either in the first aid section or ask at the pharmacy counter.
I used to have to have dental treatment without any anaesthetic (don't ask!) and I found deep breathing pain management techniques really helped. You might be able to find a technique that would help if you google.
Also, putting something cold against your jaw. A cold gel pack, pack of frozen peas or a hot water bottle with ice and water in it. Don't make it too cold, just cool. You might need to wrap a tea towel around to reduce the iciness.
Sometimes warmth helps instead, or applying gentle pressure. Try things out and you might be able to relieve a lot of the pain.
Hope you can get an appointment soon.