Hiya,
as far as travelling with my son in Europe, we did what Christy said, and took sachets of formula. As my son was 18 months, I wasn't too fussed about sterilising. most of the time we were in the UK where the water quality was good. i also bought UHT millk and definitely in Spain I used that as the water was terrible. We also bought bottled water. Avent does sell bottles that you can put a sterilised bag in, so you dont have to worry about sterilisation. Maybe worth looking at that?
Customs on the other hand, is another issue. They make to taste everything that you take for babies. So we had to open jars of food etc and taste them. i recommend taking some jars of food as that way you have something as backup if you need it.
We took an old car seat from home with us, but most places we caught trains. So we only used it when we hired a car for ourselves. Not ideal, but for the hotel transfer in Kuala Lumpar, DS sat between us with a seatbelt on, as my SIL travelled ahead of us with the car seat.
Almost every hotel has a cot, so you shouldn't have to worry there. We took a portacot with us, as we stayed mainly in self contained units or with friends so we needed one.
As far as baby products go, if you are going to be in the UK first, stock up at a shop called sainsbury or at tesco's. They sell everything that you will need. As far as Europe goes, there were still quality products, just a bit harder to read sizes etc. Most of the time I worked it out though. Every country we went to had fairly good baby products so you should be fine.
Most of all enjoy! we had such a great time with our DS