For an accurate quote all you need to do is supply the following 3 bits of information:

1)  How long will you need me? (Approximately)

2)  Where is the Venue located?

3)  What are your requirements?
1)  "What is your fee?"
2)  "What areas do you cover?"
As a full time professional, I happily cover most of the UK  and should I not be available for the date you require I will always suggest other experienced professional colleagues - so there will always be someone to fulfill your requirements.
3)  "Any Other Costs?"
No other costs - The fee quoted will always be the correct full fee.