Hi Andrew,
Can see why your smitten the 147 is a beautiful car.
I owned a 2002 5dr manual from Sept 03 until May 06. Bought it with 12800km and sold it with 44000km.

It was a stunning looking car in black with sports leather, sunroof and 17inch wheels.
Some feedback

Oil consumption - Mine was using about 800ml of oil every 3000km and this was normal. This was a talking point with the dealer who serviced it, as while Alfas tend to drink oil anyway, 147s use the most due to the low friction type piston rings used when compared with the 156 which uses the same engine. The owners manual recommends using  10W/40 for normal use and 10W/60 if the car is driven hard but most dealers were using and recommended 10W/60.
Experimented with various brands and whether I drove it normal or caned the crap out of it no real difference in consumption, so just keeping an eye on the dipstick will become habit mate.

Good to see the belts been done as this would have been the first recommendation, so great just remember needs to be changed every 60000km or 3 years........

Tyres/wheel alignment - what wheels has this car got 16s or 17inch? I was lucky as I scored a spare set of 16inch Selespeed mags with the car as it became common practice to alternate between the two, reason is the car looks hot with 17 inch wheels but drives far better with 16s. 147 is senstive to tyres and with a 17inch directional tyre the car is prone to tramlining and gives the car a slighty nervous feel to it, with 16s there's greater stabilty better handling and a better ride to boot. My car had the factory 17inch Pirelli P7000s yet when I first saw the car the previous owner was runnig 16s for the same reason. Also found I was doing wheel alignments more regularly but maybe Im just a fussy fart.

Check suspension bushes especially in rear as my rear control arm bushes were rooted at only 40000km and the steering rack ends which wear out, also changed at the same time. If the car darts from side to side or the tyre wear looks dodgey then it could be this. I was a bit suprised and dissapointed in this as the car was well looked after yet these issues were occuring at such low kms and early in the cars life and yet it was serviced by the book and then some.

Apart from that (theres probably more) the 147 is a great drive with a fiesty engine and practical too. Theres plenty of features and unlike the 156 the aircon works well(actually works!). Also the selespeed has the Bose sound system which rocks.

Hope I havent put you off but just make sure you check out this or any 147 from front to back and remember an Alfa might need more attention but theres big dividends to be had that other cars cannot deliver. Also my car was a March 2002 build yours is 2003 so maybe some the issues have been sorted out as its a later production.

Good luck and hope this helps
Cheers
Pep