I've just been through this...
Removing the starter is tricky, it's held on by two bolts that you have to get under car to get at, and i need a long extension (20cm)and a flexi joint on a socket to reach and remove the bottom one, i used two extension bars to get to top one. Space is tight too, you can't touch the bolts easily. Then there is a nut (easy to reach) to remove so you can take the battery off (disconnect it first), and one small plug holding the wire to turn the starter on. I undid the clips holding the fuel lines in place then that gives enough room to wiggle the starter down out of the bottom of the car.
Getting the new one in is fiddly, you need to get it through the gap, then balance it so the flanges line up with bolts and tighten it on. I managed the job alone, but if you know someone with long thin arms who can reach in from the top and hold the starter in place it'd be much easier.
Fix the bolts, (try to torque them the right force, about 38nm i think, but check that) put the power feed and plug back on and you're done. There's not much to do, but it is tricky so be patient.
I ended up taking mine off a few times, i tried to repair the solenoid, but the kit i got from ebay didn't have quite the right terminal on (one's straight, but the other should be offset slightly, both were straight in the kit) so that i had to take it off again, i bought replacement starter, fitted it then realised that the plug was different...finally i built one good starter from the new and old ones, and that went on and is working fine.
It should take you a couple of hours to do, and it'd be easier on proper lift, i was working under ramps and space was a little tight but i managed.
Oh, and check that the everything fits before you bolt it all back up....
Thanks very much for your help. It sounds a tad too complex for me. I'll get it jump started by the AA and get a garage to do the work for me. Thanks for your help though.