[Lord Nikon]

I use Callcentric.com - it's american based, but provides a DID (Direct Inbound Dial) number for $5.95 / month (including UK numbers, I have an 0161 running from it) Voicemail on mine is free, plus it emails you the voicemail as an mp3 attachment meaning you can store / archive your voicemails easily, and they run a PAYG service where you topup from $5 upwards and can use it to make calls. These are charged at $0.02 / minute to UK landlines and $0.17 to mobiles. (about 1p/minute landline, 8-9p mobiles)
Call quality is excellent, bring your own hardware or software, support is only available via their web page report system, but the few issues I have had (mainly teething problems with their network) have been resolved within a couple of hours regardless of what time of day or night I reported a problem.
You can also set up multiple DID numbers without an issue.