I'f you have basic mechanical knowledge it's not too bad.. It's getting to it that's the hardest part. Luckily a friend of mine who's a mechanic checked mine for free, he got it on the ramp though, took him about 15mins but was still a bit faffy on the ramp.
£105 Is ridiculous. If you're not confident on doing it yourself, I'm sure a specialist garage would do it for a hell of a lot cheaper than that