There is no camcorder in your price range that will handle low light well. In fact I’d go so far as to say there is no camcorder under £2,500 that will handle low light at all well.
DSLRs tend to be better in low light than consumer camcorders but you are right, the onboard audio is piss poor and the ergonomics are terrible.
Be aware that the audio on even expensive DSLRs (and I mean, way above £700) is equally terrible. DSLR audio is just terrible full stop, no matter what you pay. There’s a good reason that Panasonic has just launched a separate attachment for their new GH4 specifically to handle audio (and the attachment costs around £1,200 on its own!)
I do have some good news however. You don’t need to go to great extremes to shoot with a DSLR and get decent sound. You just need a DSLR which shoots video (quite feasible within your budget) and a Zoom H1 external recorder (£90) or similar device.
What you do is record the decent audio on the Zoom and a (poor quality) guide track on the DSLR, then replace the DSLR sound with the Zoom sound when you edit. It’s very simple to do and there are lots of online guides on YouTube etc.
As for which DSLR to get, it’s hard to be specific but Canons are very popular. Just make sure that it can shoot 25p or 50p as this is the UK standard (rather than the US spec 30/60) if you want to put your footage onto DVDs, and that you can adjust all the settings while recording (some only let you set the settings while not actually filming)
We recommend a read of this article too: http://dslrvideoshooter.com/best-dslr-for-video/