I'd always recommend using a different company to buy (lease) the domain name from, rather than using the server company, apart from the cheapness of such companies as "123", there are potential problems if you do an "all in one deal" -I found out the hard way!
In simple terms, I had about 4 domain names and server space all from one company, and I had signed up in the first year they were trading - at first they were great, and I was on first-name terms with the bloke running it - sadly, as it grew larger, the service became atrocious and frankly obstructive- following a spate of "site down, we've all bogged off for the weekend - tough" outbreaks (which meant they had broken any agreement they had with me), I chose to move my sites elsewhere - he then demanded vast sums to release my domain names to another company, and I had to "go over his head" to Nominet to get them back......... Nowadays I use "123", so should I have the same problem again with a server company, I can go online and point the domain names wherever I like.......