I've not done this in years as I've taxed online for a long time but I actually had the conversation with someone the other day why they cant check your insurance online in the post office. Seems someone has wondered why too!
http://www.pistonheads.com/news/default.asp?storyId=26516 (http://www.pistonheads.com/news/default.asp?storyId=26516)
haha. not just me who nearly always forgets about it till the last day then?