As you are in the UK just enter Rhododendron Sun Fire into a Google search and you'll come up with lots of places that sell...

There are no UK suppliers currently listed on Plant Finder.

J. Parkers are currently offering it for £9.99.

I would beware them on past experience.

I don't do internet shopping but my sister and a friend both got good service from them. On the one occasion when she complained about something it was sorted out quickly. She has not used them recently.

From my experiences with them, Parker's bulbs are OK but their plants tend to be very small.

I ordered some yellow anemones that they advertised as flowering all summer. They flowered in early autumn autumn and were a sad pink. I complained and they replaced them the following season - with more of the same.
and the blueberry shown as a lovely big bush in the catalogue was a tiny one. Their bulbs are OK but I wouldn't buy plants again. A lot of their stock is bought in too.

Any catalogue with pictures of blue roses or blue tulips is suspect.

Roses shouldn't be blue anyway. Blue Moon is a particular un-favourite!

Thanks to you all. I have looked and can only find J.Parkers as someone has suggested. It's for a present.