These replies are not in strict order, so many people have commented, trying to reply to as many as possible but getting a bit jumbled! Hope anyone who wanted a reply from me gets one!
firefly having my wisdom teeth out was not painful, not pleasant, but not painful if I recall rightly. What was painful was my crap boyfriend was due to take me home and for some reason did not n=so I went hoem by train and had not roper pain relief for when the anaesthetist thing wore off. make sure you have the things in place. I also had all four out at same time so had no 'side' to eat on and had to have my food mashed and my drinks through a bendy straw. Food doesn't taste so good with no texture. But if was OK, please do not worry, just be well prepared - e.g. I had time off work while I got better, I could not have just gone back to work the next day as I felt unwell, but then I was 21 and a total wuss at that time!
DefinitelyNotElsa wow that was so brave of you to make that decision and take the consequences.
stratter5 re If you don't trust him over a bunch of Internet randoms, you need to find a new one. Well, he is a she, and it is not that I don't trust her, I want to see if I am being unreasonable in questioning this, I certainly won't be asking anyone on mumsnet to do the actual work! 
MinesAPintOfTea and firefly78 I am sorry that both your mums made that choice to not have things done that would help.
I want to avoid making the wrong choice, teeth out may be the right one.
Mappa, Leigh1980 and Math so glad it worked out well for you, and all others who posted here about their own experiences.
Math I know it seems strange but I take the kids for ice cream after a dental appointment! It is about the only time they have ice cream outside the middle of summer and it is a posh delhi that sells a special kind of ice cream. It is a treat for them, not a reward for whether they need treatment or not etc. So T totally understand your mum taking you for sticky meringues and the fact you remember that and not the pain, is great! 
TotalConfucius and DeoGratias so glad it worked out well for your kids, and all others who posted here about their children.
OTiTO re I had a thumb sucker. The dentist put a ring on his thumb and he completely stopped in a few days. Could you put a cast on the finger to break the habit. I was amazed how immediate my DC lost the habit.
RandomMess re 8Long socks over BOTH hands taped around the wrists. Expect several nights of your DD finding it hard to get to sleep and stay asleep but it does work.* I will try it, I am afraid my dd could be an escapologist but I will not be defeated!!!!!
Hulababy yes, But it depend on which teeth and why they need to go surely? I need to find out why, I was not expecting it and it was all a bit of a blur!
Wow, excellent, by a cast do you mean like as if it were broken? What kind of ring did they use? That is an EXCELLENT idea, we have tried with gloves or socks in bed, on the hand, that anti thumb sucking thing you tie on that she worked out how to undo, that foul tasting nail polish and I tried reminding her, not reminding her, commenting on it, not commenting on it, showing her pictures of people with misshapen teeth on the internet, but I never thought of a ring! INSPIRED.
Mrsmorton re ... 24 teeth isn't unusual, just gives you no room for error if you need teeth out in the future. Can you say more about this please, do you mean if dd lost a tooth any time that having fewer teeth could make it harder to 'repair' or having more teeth could make it easier to 'repair'.
There have been so many replies (which I was not expecting) so thank you all, I am sorry if I cannot mention all names but I am VERY grateful for all replies.
Just for the record I am not worried about my daughter experiencing some pain or distress temporarily if it is necessary. I am not being 'precious' in wanting to avoid this treatment, I am concerned that it may not be necessary and I want to make the right choice. I don't think anyone has accused me of being precious' (yes she is my pfb), but in my own mind I am wondering, should I just accept was is told to me by one professional? But I know in my heart I cannot, I always like to feel I have made an informed decision if it matters, an in this case it does feel like it matters. I think I should ask the orthodontist why the teeth need to be removed and seek a second opinion.
I might also see if I can get a private consultation for just a second opinion. I wonder how much that is going to set me back!
EddieStobbart re My DD (9) currently has a removable plate to help her stop sucking her thumb. The orthodontist thought it was worth starting preliminary treatment now although she won't get train tracks for a few years. ... Could you get a plate before the brace and see if it helps? I was told this was not on offer on the NHS and would cost a lot, and may not be available from our orthodontist anyway, I did ask specifically about this. Trouble is we have been on this journey already about 18 months and i can't remember exactly what was said, I need to get an email from the orthodontist so I can mull over it, I do find conversations by phone a bit of a pain about medical stuff because once it is over you can't always remember all the details. I must ask about this when I get the second opinion. THANKS SO MUCH.
MackerelOfFact re What are your friend's dental/orthodontic qualifications? I think none, except that he can read things on the internet. Re By all means get a second opinion, but I'd suggest getting it from an orthodontist rather than your friend. definitely will! 
If anyone would rather PM me about this stuff, (e.g costs of treatment etc), please do.