Hi Soph,
I am a qualified dental nurse.
You shouldn't have ANY pain whatsoever when you have a tooth extracted. If you feel any pain, you must tell the dentist immediatly and they can give you more Local Anaesthetic. You WILL feel pressure and you WILL hear cracking/crunching noises, this is absolutely normal, do not panic.
You could also ask if the do relative anaesthesia at you dentist, which is basically G&A (like what you have in labour) it calms you down and makes everythinga bit hazy.
If you are really really scared, you could ask to be referred to your local hospital and have it done by a surgeon under General Anaesthetic.
But honestly, its really not that bad at all.
Can I ask which tooth it is that you will need out?
There are several options other than an implant if there will be a noticable gap between your teeth. I would go for an implant as the last resort as they are very expensive.
First option would be a plate (false tooth) I know what your thinging!! Urgh, dentures!! But if it's just for the one tooth, it is tiny and you wouldnt even notice its there.
Secondly, if the two teeth either side of the one you need to have out are healthy teeth, you could have a bridge fitted, which is two crown on either side of the gap and a 'false' porcelain tooth where the extracted tooth was.
If it's viable, the bridge is certainly what I would go for before an implant. Implants are very expensive and require a fair bit of surgery.
Hope this has helped