Great Western Coffee Shop

If I was looking to hire a coach ... around 30 seats, school holiday, early start and late return to Melksham.  150 miles out, 150 miles back ... what sort of cost am I looking at? ... as a one-off? ... as a weekly thing all summer?   Very casual enquiry at the moment - looking for an order of magnitude and I know we have some people in the know.   Web sites seem to give me a quotation form to fill in  :-\

When we got married back in 2011 I got some quotes for guest transport. We didn't follow through with the idea as only about 8 guests showed an interest in using it.
For full day hire with around 40 mile round trip I was getting quotes between ^200 and 300 which included the coach, driver salary and mileage.
The breakdown for most of the quotes were around ^100 for the coach per day, the drivers salary which varied between ^8 and ^10 an hour, and around ^1 a mile seemed to be the mileage rate - mileage was calculated depot- pick up - destination- drop off - depot.

So:
100 ... coach basic hire
300 .... 300 miles at 1 pound per mile
140 .... 14 hours at 10 pounds per hour
===
540 pound for the day

Thanks  ;D

14 hours may require 2 drivers which may complicate the calculations.
There may also be a better chance of negotiation in school holiday as a typically quiet time for operators especially those with a lot of school or college contracts