This is only in relation to the original poster and not other members that have commented....
If you dont feel overly confident and haven't fitted springs onto the car before, I would recommend you pay someone like JKM do fit them. There is a lot that can go wrong, you might cost yourself a lot more than £200 if its not done right. It can easily cost you £200 in tyres if the tracking is not done right.
Companies like JKM are not there to rip anyone off. they are there to provide a professional service, get it done right first time whilst at the same time feed a family, pay for a mortgage etc. Your not being ripped off, £200 is a fair price when you think of all the labour and tracking that needs to be done. Your paying to put a daughter thru university or a to put tea on the table for someone like JKM, not paying for yachts and fancy holidays.
thats just my opinion. By all means, DIY if you are fully confident, if not, get the professionals in!
Oh and you other members that I said i wasnt addressing, Im more than confident there are a lot of our members that would be able to do this themselves ;)