How should my availability page work on my new website?

I could put up dates, lets say for the week ahead and blank out the days when I am definitely NOT available. I know my dad is coming to visit one day, for example, and my dentist appointment another afternoon.

I know one of my regular clients is visiting me on the Friday morning, so I can mark that as not available too.

BUT

what about the other appointments in my diary?

You see some weeks I may have 3 or 4 appointments booked within the next 7 days AND sometimes everyone of them cancels.

Yes not one of them turns up but thankfully at least the vast majority of clients do let me know one or two days before.

If I had blanked all of those spaces other potential clients viewing my diary might not contact me as they think I'm fully booked.  so, I might leave those dates as available even if there are bookings unless I am very confident the client will attend.

From what clients tell me they fall into two categories:

1. Those who can book ahead and like to work this way, there visit to me will be timetabled to fit in with work or specific events.

I must admit I also like to work this way.

2. Those who can only book at the LAST minute - the night before or on the day.

Due to work and other pressures.

Last minute bookings don't work well at the moment so it would be really good to have a better method for those.

I am thinking that what might work for these men is to just know for definite whether I have availability within the next 12-24 hours.  They are not interested in 3 days time.

Thinking as I type here - 

1. perhaps I could put an indicative diary on an availability page.

AND

2. update my availability for the next 24 hours every evening (perhaps 6pm ish) on the very front page

 ****   By the way - it is very rare for someone to simply not turn up but it does happen - to quantify I estimate about 3 times a year. *****  If you are one of those men please have more consideration, it is not normal, most men do not do that.  I could not continue to make a living if everyone did that and as I only usually see one client a day then someone else will have missed the opportunity because the time was held for you.