This always seems to be a hot topic on a lot of forums so I thought I'd share my recent experience for the benefit of anyone else thinking about this and perhaps over time others will also add their specs for reference.
Anyway, I've added 15mm rear and 10mm spacers to the front. This gives me an effective offset of ET35 front and ET30 rear with a 8.5x19 rim.
Here's a few pics of the finished article...
before spacers (ET45 all round):