CutCutCut: I put in a TP Link modem/router in for my in-laws and it has been really good, but they only have one apple device. I know a lot of people recomend the TP Link gear but I don't know how apple friendly it is, maybe other have more experience.
As I said in my OP, our router was working well prior to Christmas. But since then it has had its Wifi workload increased with an extra two iPod Touches, an Apple TV and two Android phones connecting. Its since then that reliability has taken a significant nosedive.