by isb » Apr 10th, '13, 21:20
Have a look at the Sennheiser Freeport radio mics. I think they are discontinued now, but it is/was the budget range from one of the market leaders. I have the Presenter version with a clip-on mic which is fine for my use, but the transmitter could easily take a discreet headset mic as long as it had Sennheiser's threaded jack connector. It also comes in a version with a handheld mic transmitter (and a version for an instrument with no supplied mic). It's a UHF Diversity system - two terms to look out for.
Some of the cheaper ones are in the VHF frequency range - many of these are acceptable (my handheld is a pretty good VHF system) but I'd not recommend it. Go for a UHF system.
I wouldn't buy a radio system that was not Diversity. Simply, a Diversity system has two separate receivers to mitigate the risk of reception problems or dead spots. Note that not all systems with two antennae are diversity systems - if it doesn't say it is a diversity system, it probably isn't.
The Freeport has 4 frequencies to select from (may not be compatible with other existing transmitters or receivers) and you shouldn't need any licence to operate them in the UK (unless you get a grey import, so best check). If I remember correctly they sold for about 130-150 new. I got a barely used one on eBay for about £80 a couple of years ago, though I did need to replace the mains adapter.
PM me if you have any specific questions. I'm not a sound tech so may not have all the answers, but I do own a small PA that I use for speech, music etc.