As Allan says the rear bush is also shot(sorry,should have re read before my last posts now I have wifi connection) then yes the wb has to come off, obviously.
It is far easier to press a front oe bush in, than press an old one out ime. And easier still to cut the old one out. Weather on the car or off it. Cutting the outer metal ring of the old bush is the critical part, and obviously stopping short of cutting the wishbone is key. Cut as deap as you dare then chisel and hammer to force the bush outer in on itself while tearing the remainder of the hack saw cut.
There is a perfectly clear guide posted by razzo if you care to look...? :-?
AA had his pollys fitted in a field at Newent in about an hour. It's not difficult or dangerous in any way...(wtf? :-? ) although cutting by hand with a hack saw is extremely tedious, granted.
Chris, you can do as you wish, but I dont think a garage who works like that can take a quality certificate 
Why not? So they can charge 4 times as long ? 
It is the recommended way, ask master. And when you "press out" a front bush please post a video. I will be most interested in your first attempt
years ago when I first replaced the front bushes only (it was boge) it didnt go longer than few months.. changed another time.. second set lasted a bit longer.. all changes done on a big hydraulic press, so it was easy.. however as they didnt last well , I bite the bullet pay the money and buy original GM which last more than 50K (kms).. after that , I give up to pay this money and buy wishbones thats produced in my country which was 1/3 of that price (original GM 380 £ approx) .. its been a year and no problems so far..but I'll try those poly bushes also..

ps: I dont think those wishbones will be safe if bushes changed even with a hyd .press more than a couple of times.. :-/