Build a booking website for a small community hall

I need a quote for our local Rotary Club in Australia that will have an online booking system for a small community hall that we maintain. We would like it to have an integrated payment gateway that does not allow bookings until payment is approved to take the onus off the treasurer having to confirm bookings. The calendar for bookings should be publicly available to show that it is available not available but not with details that the public can access. However a rotary member with the access code should be able to log in to the back end to check on the details of bookings. Terms and conditions need to be agreed upon before the hire is booked. We have a code on the door which is changed monthly so it needs and easy to change system (for a non-techy person) for notification of the new code with bookings - perhaps with something like a reminder email from the system a day before with the code to access the facility in case they book it in advance. Ongoing costs for the reservation system and payment gateway interactions would be as minimal as possible as the hall hirers ultimately pay for the running and the upkeep of the hall. We are a Rotary Club that has very few members and we would like to try and automate some tasks to save our time and costs - we should qualify for a not-for-profit rate on booking programs. Hires are only in day and half day lots with a rough time frame for both (can be changed an hour or so each way i.e. half day booking is for 8-12, 1-5. However it could be booked for 9-1 etc. But not too far outside of these hourly boundaries). There are only approximately 10 hires a month currently.