Living outside the UK, I like to use either Hattons or Rails, based purely on price and exchange rate- Hattons bargains are hard to beat.
However, in ten years of semi- regular ordering (probably a loco or three a year on average, plus other "bits"), Hattons delivery times have proven to be be quite random: despite always selecting Royal Mail Air it can be anywhere from one to five weeks. The five week item scared me somewhat. I emailed to let them know it hadn't arrived, to which I received a curt and somewhat irritating response. While considering my options, the order arrived a couple of days later. Whew!
Currently, I am awaiting a Bachmann DMU which has taken four weeks thus far. I am contemplating sending an email but may wait a few more days. Plus, I don't want to actually *not* receive the item this time; based on the above, I'm not confident in how they would handle that...
Can't beat the prices though.