I'm sorry you're going through this stress - however I'd think very hard before asking for a scan at the EPU at 6 weeks.
If it were me, then in the absence of further bleeding and/or pain (and particularly shoulder tip pain) I'd sit tight and see what happens. With the best will in the world, there's a strong possibility that the heart hasn't started beating yet (just because its very early) and so a scan at this stage would be inconclusive - and then you'd have a wait of a week or two for a 2nd scan to confirm whether the heart has started beating or not. Our EPU try not to scan until 8 weeks for exactly this reason, as very early scans can often cause more stress than they aleviate.
I do empathise - I've had 3 early miscariages. Two of them just went straight in for lots of blood, but the 3rd kicked off with a couple of weeks of spotting in varying colours and quantities. It was incredibly stressful getting through it - and almost a relief when the bleeding started properly as at least then I felt I knew where I stood.
To me, it does sound as though the sex triggered off a little bit of spotting - in which case it will all ease off. However, if you're worried then its always worth getting advice. You could contact your EPU direct - some operate drop in clinics and the 2 I've contacted have been very happy to talk over the phone. If they think you should be seen they'll also advise the way to accomplish that in your area (I needed to get a GP referal, although I'd already chatted for about 20 minutes or so). If you do decide to call it might be worth expecting to call a couple - my closest one has the policy of not having an answer phone as they can't always return messages promptly. But that does mean if they can't get to the phone you feel very cut off. After not getting through for a while, having tied myself in knots, I decided to keep ringing numbers until I got a voice on the end of the line - and they were completely unphased by the fact I wasn't entierly local :)
Re. MW's, I think they try not to book in too early as within the 1st trimester there is very little for a MW to do and they're very overworked. I wouldn't expect to have an NHS MW appointment until about 10 weeks, to give time to book the 12 week scan, so I don't think you're being neglected in that respect. Most antenatal MWs aren't specialists in early pregnancy, so talking to the EPU is a better bet at this stage.
Sorry - that's got very wafly
. Hope the spotting stops and you go on to have a worry free pregnancy :)