So I was looking at the worst part of a grand to get my car back on the road.
Well, that was until today. I woke up thinking - if it's just a cooling pipe, why not see if it's possible to replace the pipe? I can refill the system and see if the pump's knackered at any rate, and eBay have pumps (in America unfortunately) for around £100.
So I removed the old pipe (god that was fiddly), got some copper pipe of the same external diameter from B&Q, gently hand bent it and put it in place, got some more power steering fluid and started her up. A bit of a whine but the power steering works perfectly! The whine is only slightly noticable as you pull out of a junction, and is practically unnoticable when you're just driving around.
So, 3-4 hours of my time, and a bill of £40, plus a euphoric feeling of success (those who know me will know that I've not had the best of luck fixing vehicles before.. I've kind of been put off by past attempts). So this was a huge win for me :)