Personally, I would definitely take him to A&E, cus even though it's Friday night, there's not a hospital, I should imagine, that wouldn't make a priority of a child, especially one so young.
It might seem late, but never worth leaving. You won't sleep until you know he's ok.
And in my experience, personally and through work, NHS Direct aren't all that. They normally just direct you towards your own GP anyway... Have you tried ringing your own GP, who will either leave an out of hours number on an answering machine, or automatically direct you when you call. This is normally covered by your own GP, or more likely, a locally based dedicated GP out-of-hours service, so would be quicker than waiting for NHS Direct to ring back.
I know what you mean about them sleeping the other way round though...!
Good luck and do let us know what happens.
Minz