Tooth extraction looming - help!

A year or so ago my dentist advised me that a back (wisdom) tooth would need removing as it had partly broken and had a cavity but wasn't possible to fill as there wasn't enough tooth left. Have put this off for as long as possible as it wasn't causing any pain, but now bits of food get stuck in the cavity which are tricky to remove. On last check up, was strongly advised to have extraction done as it will not improve and may become infected or worse. Reluctantly agreed to this and appointment is on Friday. Last time I had any teeth removed I was about 9 or 10 (Overcrowded mouth! - do they still do this?) Have been sent to a specialist who is used to nervous patients - that's me! Any words of wisdom or comfort - from anyone who has been through it? Will be done under local anaesthetic.