Please need a letter, not able to join this year?

I have been accepted by university for year one cicvil engineering course , Dr XXX has helped me throughout to get this admission.the term has already started and i realised that i won't be able to join this year, due to a delay in getting a sponsorship clearance. i wish to join the coming year.
how can i write a proper letter , appologizing for not starting (due to sponsorship )... and thanking him for help .also leavinga window open to join the coming year ? please help me.

here is what i managed to come up with:

I would like to thank you very much for giving the opportunity to start the course at XXXX(UNI). I greatly appreciate your help.

I would like to thank you very much for giving the opportunity to start the course at Strathclyde. I greatly appreciate your help.
As you may know, I have been expecting a certain delay in attending the course on time due to finalising necessary sponsorship award documents as well as the visa entry to the UK. while this absence can be justifiable, it is nonetheless becoming great concern for me and whether I shall be allowed to start at such late time. As I am unable to obtain the required award document to enrol , It is with regret that I have to drop the course this year, hoping you would give me the opportunity to make a fresh start next year.
I would like to thank you again for taking the time to consider my application and I do apologize for any inconvenience I caused .
Sincerely.