I think you are offering a decent package with:
10 full page website
Online web gallery
Online booking form
Availability calendar
Photo enhancements on up to 20 photos
FREE domain name
Auto response on all emails
Submission to Google, MSN and Yahoo
Free online support
1 year web hosting
You could attract some customers in the UK (where everything is expensive!).
If you are charging in GBP, and targeting the UK, you may also want to get a .co.uk name.
The site definitely needs some work though, here are my suggestions, in addition to everyone elses' suggestions:
Design / HTML:
Pick one, maybe 2 fonts - I can see at least four on your homepage.
Put some styling on your text (the default times new roman is not so nice)
Look into using XHTML
Make sure your page validates:
http://validator.w3.org/
Content:
Get your story straight! the order page says to send details first, then pay, the homepage says the exact opposite. I also agree strongly with IntelBanks' point that you should not ask for blind payment.
Your example availability check takes the visitor to another site, they may not find this reassuring.
You ask the customer to send "Your rental rates per week", this may be overly simplistic. What about different seasons? Day rates? Different rates for week days / weekends?