Its actually very easy and you are less likely to mess it up than a mechanic(specialist excluded) also you will take your time something that most garages are against(time=money) as the back seats have to come out...a massive 4 screws if I remember correctly,2 for bench and 2 for the back rest ones. My GTV also idles so much more smoothly with the new fuel pump fitted. When refitting remember to change the green rubber seal from the old pump to the new one and don't over tighten the cap(use a hammer and a lump of wood 5" long or so, tighten slowly then drive for 10 mins/run engine with back seats off turn car off and open the fuel cap and see if it gets the wooshes noise its tight, if no noise it needs to be a bit tighter. Only then refit the seats. if its not tight enough you will get a petrol smell in the car after a drive.(from the recirculation vapor trap)
There are videos on you tube of Alfa 156 having their pumps changed in some eastern type countries(probably due to the increased sand and dust blocking them) and its basically the same. Have a look.
This exact situation happened to me!