When I try to view the radar display it just sits on 'loading' and I can't view the full sequence

If the radar fails to display a full sequence (instead showing, say, the first frame only), it could be that your PC is preventing javascript from loading further images. In internet explorer, be sure that in 'tools'->'internet options'->'security' and also 'privacy', that the level is set no higher than medium.

Third party software such as 'internet security' or 'adblocker' software can trigger the same behaviour. Make sure when using such software that this domain is considered to be a trusted site.