If you know someone mechanical its time to ask them for help, make sure you accurately check those holes, its only 2mm either way - not like a obvious difference.
Id imagine around £60 to fit the shocks ould be around right, its not a terribly hard job if you have any mates who have some idea... your going to need spring compressors etc aswell as a decent toolkit.
That Max power clio book thing has how to do the job in (along with loads of complete sh*te) not sure what you mean by circa clips? everything you should need is with the dampers( your meant to replace the top caps aswell - i havent)
£100 sounds about right for the pair