Many 2.1 'active' speaker systems are not true actives - a decent satellite speaker will have two drive units, sometimes more, yet typically only one amplifier channel will power the satellite. If you can accept that, then I'd suggest the Altec Lansing MX5021 system that I have used and been pretty impressed with (for a price of under £150). Will be difficult to track down though.
If you're feeling more adventurous, you could purchase what I believe are currently the cheapest true active studio monitor speakers on the UK market - the Studiospares Seiwin monitors - then add a cheap subwoofer.
I can vouch for the Seiwins as I use them (they are amazingly revealing for around £137 - check out reviews). I don't however use a subwoofer so have no idea what quality youd get for around £113 or how versatile connectivity would be although I notice Thomann are selling the Behringer B2092A active subwoofer for £129 which has been well reviewed you certainly appear to get a lot for your money.
I suspect youd have an unbeatable (and very powerful) 2.1 setup with the Seiwins paired with the Behringer sub at just £269 total.