Just wanted to update - I have just received a phone call from the DVLA, who have confirmed that I am able to drive past the 15th May, despite being a HRO. This is because, in effect, being issued a license means I am no longer in the HRO category for license renewal, but am in the medical 'pile' like anyone else. The lady admitted the wording wasn't very clear, but said as long as you are confident that your GP has no issues with you driving, you can continue.
I will put this on a seperate thread as well, as I'm sure as this drags on, more and more people that were HROs will be coming to the end of their respective temporary licenses. Just goes to show that not all the advise you get on here is accurate, even from those who think they know it all!