have a look here, I have just googled it:
http://www.netdoctor....ndallergy/201292.html
It's a steroid so is only recommended for occasional use, not as a routine cure for hay fever. The date on this article is however 2006 - so it might be delicensed now, or too expensive for use in general practice.
Risks
http://www.netdoctor....ndallergy/202481.html
However read this one too, it looks like you are not the only one being refused treatment this year -
http://www.netdoctor....opic.php?t=55333&f=31 - which suggests to me that there is now further evidence that long-term usage might be risky.
Your GP should explain why this medication is no longer available to you, if you have had it before - yuor previous treatments will be on your medical record which will have transferred with you when you moved doctors.