Ok this is no problem.
More panic will make it worse, just remember its nearly £200 including VAT your playing with and it will help
You need to go and buy a set of eazi outs and a tap wrench.
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0446853A tap and die set wont do it you will make it worse and the thread is probably a standard pipe thread or even a special fine thread.
Don't panic, we can help I have a spare pump in bits if you need anything.
If the worst comes to the worst I will try it for you, but you will have to send it to me.
I would suggest getting the rubber pipe version instead of the hard pipe, you can check the cam follower very easily without removing the pipe then.
The guy who sold me my spare pump had another one to so loads of options.