I have been in contact with both Honda(UK) and my local Honda dealer. The Honda dealer was most helpful and said he would check and get back to me. He did and confirmed my findings that there are very few tyres in the Crosstar size available on the UK market. In fact none of the premium tyre makers (Michelin, Goodyear, Continental, Vredestein etc) make any tyres in the Crosstar size.
Honda(UK) replied that they would investigate the situation and get back to me. They did, but just to confirm the tyre size and explain that the Crosstar size was to provide the correct comfort and technical requirements of the Crosstar. They would not address the tyre availability situation (or lack of availability).
So there you have it - buy a Crosstar and accept your choice of tyres is so severely limited there is no choice. Incidentally I also contacted a UK wide tyre supplier to see if they had a solution. They not only told me there were few to no tyres available but told me that if I ever had a serious puncture needing a new tyre I could be waiting some time before they could source one!
You have been warned. I am thinking I should write to every car magazine and ask them to warn their readers of this situation. perhaps Martin Lewis as well.