I am not a dentist, but have had a bit of a saga with my teeth of late and am both a very nervous patient and phobic about needles so I really sympathise.
If you are in awful pain, you need to call whatever NHS 24 is now. They will either be able to put you on to an out of hours dentist, or give you a list of surgeries. (I don't know how this works personally as I am registered.)
I had both a root canal and an extraction in the last three months - both the same tooth. In my case the dentist couldn't find every canal and the tooth never settled, so it flared up again before I got the crown. I could have had it redone by a specialist at a cost of £300, but by that point just wanted an end to it. Mine was a back tooth.
Root canal - uncomfortable and boring, long, but not painful. I found the whole dental dam thing really claustrophobic. I have a previous root canal which worked fine, and if I had to choose between that and an extraction, I would try to keep the tooth.
Extraction - quick, but hard going in my case. My tooth didn't want to come out and had to be sectioned into bits. However earlier this year I had an upper wisdom tooth out, and it was so fast and easy. Each tooth has a different configuration of roots which makes a difference.
Healing - if your tooth is infected, treatment should alleviate infection. I'm six weeks since my extraction and most of the gum is healed over. I still rinse with mouthwash after eating at home, but don't bother at work. It's probably more habit now than needed, but sometimes food can get stuck at the wee bit which is not covered over.
There was a thread a few days ago about calming nerves before dental work which I wrote my tips on, and other people were really supportive to that poster. I'll see if I can bump it for you.