The Eternal Question - Reaching Usage Limit options.

[#1]

How terrible are the "restrictions" placed on your line once you pass your limit? I did a silly thing this week when activating a new phone and redownloaded a load of Apps to it that I thought wouldn't affect my usage that much.  1.76 GB later I'm a Gnat's Crochet now from hitting that Glorious 10GB limit.  Do I pay the penalty of an extra fiver's worth of GB's?  Is it worth it for a one off? Can you do that for just one month?  Or are the restrictions liveable with for just the 5 days we have left in this month before our new billing date starts?  Currently on 9.37GB
What would you do?

[#2]

256kbps up and down so normal browsing and email is reasonably OK
yes you can do it just for one month

[#3]

Thank you.  Well, it's faster than dial up I suppose! (Fond memories!),