In reply to Luke90:
Ah - it hadn't occurred to me to try it on my phone, dur!
I tried two different laptops and was getting everything except the map itself, just a blank screen. Same thing on the phone on wi-fi but then I turned that off and it loaded ok using mobile data, and now seems fine with the wifi back on again.
Weird, but never mind, I've found the answer to my question now thanks.