OK Boys and girls, all done!
I know this has been a bit of a nightmare job, but that is only really because it was the first time I've ever done it on a 147, in reality the only real problem is removing the old stuff, with hind-sight I will now try and give a step by step guide on how to remove a front wheel bearing on an Alfa 147 with the hub assembly still on the car (without going into ovbious stuff like jacking the thing up!)........
1) The first problem you are going to have is removing the hub nut, so, first thing to do is remove the brake caliper, but leave the caliper barcket securely in place. I just propped my caliper up on top of an axel stand.
2) Bash the tabs on the hub locking nut out of the way of the driveshaft key-ways.
3) Re-fit the wheel bolts and place a piece of bar (I actually used an allen key) between the vanes in the brake disc and the bracke caliper bracket. This should stop the hub turning while you are trying to undo the nut.
4) Using a 36mm socket and and the longest breaker bar you can find, slowly undo the hub nut (anti-clockwise)......if you get no movement at all, heat up the hub nut (I used a plumbers propane torch), it is getting replaced anyhow, so dont worry about damaging it.
NOTE: It may be benificial to turn the steering to a better position to allow more force to be applied than is possible within the confines of the wheel arch.
5) With the hub nut removed, the brake caliper bracket, brake disc and shield can now be removed from the car.
6) Use a pieces of flat metal bar (I think the ones I used were 10mm thick) placed between the hub assembly and hub flange, insert the wheen nuts into the hub and wind them in slowly and evenly.
The metal bars effectively give the wheel nuts something to push against, and winding the nuts in slowly will push the hub flange away from the hub carrier.
Once you get to the end of the threads on the wheel nuts, the hub flange should be sufficiently far enough to be "persuaded" out with a hammer on the back of it.
Before I used this method, I tried a hub puller, bearing pullers and all sorts, but because the drive shaft can move, all this does is move the driveshaft further through the hub flange. The hub flange itself doesn't move a bit!
7) With the hub flange removed the allen-head bolts that hold the bearing housing in place can be removed.....
For this I used an 8mm Allen key with a ring spanner threaded over it to allow much better leverage.
Once the bolts are removes a pry bar, long screwdriver, chisel or whatever can be used to knock the bearing housing from the hub carrier, again this is now a useless part, so damaging it won't matter.
Also, simply hitting an allen key with a hammer got me nowhere, and an allen key socket I used actually snapped, so thry to avoid "shocking" the bolt loose. I would also avoid heat with these, because if the bolt snaps you are screwed!
8) If like mine, you have pulled the centre of the inner bearing race out with the hub flange, grind two slots either side of the race (this will be binned anyway) to allow a bearing puller/hub puller to pull the race from the hub flange.
I couldn't remove the race off my hub flange with heat, and because of the smoothness of the bearing race the pullers wouldn't attach to the race without grinding the slots in it.
And that's the hard stuff done!
To refit the new bearing, simply bolt the bearing housing onto the hub (taking care not to bend the ABS sensor), tighten the new allen bolts to the correct torque. If you got a bearing without the bolts, just locktite the old ones, thats probably why the old bolts are such a pain to remove in the first place!
Offer the hub flange to the new bearing and evenly and gently tap it into place until the hub nut can be threaded onto the driveshaft spline, refit the brake disc shield, caliper bracket and caliper, again insert a piece of metal bar between the brake disc vanes and the caliper bracket, then tighten the hub nut up to the correct torque, and bash in the nut so it "crimps" the end of the drive shaft, and I think that's it!
I may of missed something, and if you want to know, just ask......
There will no doubt be other methods for doing this job, but these are the ones that I found to work