Letter to a friend

Dear Mahoud,

Hope you are doing well.

I would like to apologise regarding the my arranged visit in Jan, *I won't be able to make it! As you know, I was looking for a new job as I was not happy with my previous position. The problem is that Now as because I got hired the job I will not be able to take a vacation till August. which Since it will be summer season and we can make other arrangements like camping at the beach.

I hope you will not be busy at that time.
Please pass on my greetings to your family and let me know if you can't make it.

All the best,
Ahmad Abdan

*You need to say why you are apologising, it sounds a little strange just to apologise about a visit.  Between friends, something like "I'm really sorry but I won't be able to visit in Jan like we'd arranged."