That actually looks like a pretty nice system, and most likely would make a good addition to your TV, and would be reasonably good for casual music listening. Though don't be overly impressed with its claim of 800 watts peak. If you look deeper into the specs, it is two 50 watt channels plus a 100 watt Subwoofer. Though that is still very good power for a small system like this.
In the UK, you will typically find mini/micro amps in roughtly the 25w to 30w per channel range.
If you want basic stereo, for £300 you could probably do reasonably well in a basic separates system.
However, if you feel you need a CD player and iPod connectivity, and perhaps AM/FM/DAB radio, then for that budget, a Mini/Micro all-in-one is about the best you can do.
In the UK, I don't recall seeing any of these systems that come with a subwoofer, though some of the amps do have subwoofer outputs.
The Denon DM37DAB seems to be a popular model, though it has a base price of about £199. Others to consider might be the Onkyo CR-435UK and the Yamaha CRX-D430, and possibly the Yamaha M-430 all also roughly £200.
[EDITED:]
Here is a discussion of the Denon DM37DAB -
Denon DM37DAB new mini star?
. . . . . . . . . . . . .
If a Subwoofer is important to you, then get an amp with a subwoofer output and add the sub later.
To these amps, you could add a pair of Diamond 9.1's or Tannoy Mercury F1, both just under £100 per pair. Likely, you can find pre-packaged deals on any of these amps with these speakers at an improved price. If you really want to save money, then consider Diamond 9.0 on the assumption you will add a Sub later. The Diamond 9.0, if you can still find them, can be had for a mere £50/
pr.
You will see a lot of these systems bundled with the Q Acoustic 1010i. This is a nice speaker, but doesn't have the deepest low end response. However, if you are determined to add a Subwoofer, that doesn't matter that much. These speakers combined with a matching sub would do a good job, and the speakers in general are well regarded for surround sound system, again, where they are matched with a Sub.
The Sony system I mentioned earlier, and similar, might also be worth investigating.
Teac systems, while they have a generally good reputation, I'm not so sure about. I've heard a few negative things about them, but mostly that the remotes are inconvenient to operate.
I don't really follow mini/micro systems, so I'm not that knowledgeable. Perhaps some with more knowledge in this area with weigh in and expand the discussion.
[EDITED:]
I did just find an iSymphony UK website, though the model you are interested in doesn't seem to be listed there. The model M1 and M2, as well as the MS1, seem reasonably available in the UK, however, none seems to come close to the M210X model you suggested. I think the closest would be the UK model M210E, but this model in its stock configuration does not come with a sub.
http://uk.myisymphony.com/products.htm http://uk.myisymphony.com/products_m210.htm
Note the M210E doesn't seem to be available in the UK yet, and I notice that it does have a Subwoofer output.
Steve/bluewizard