Well, the core question is, if you only have £200 now, how much are you going to have in the future and how soon are you likely to have it?
I do know that the Jamo's are extremely popular. They are likely one of the fastest selling speaker systems out there today. If you search the forum, you should find many threads on them.
What you need to do is to go to SuperFi or similar sites and see what you can get for £200 in a pair of speakers. Certainly Wharfedale, Epos, Kef, and Acoustic Energy all fall into that range.
For better, in roughly £500 to £600 5.1 systems, the front speakers are actually cheaper than £200/pair. In this category, you are likely to find Quad, Q Acoustic, Wharfedale, Mission, Mordaunt Short, and others.
Next, you have to decide how you want to upgrade. For me, my next upgrade after the fronts would be a Sub to give me a first rate 2.1 speakers system. But, my main interest is music. Then add center and rear when I could.
For others, more into movies, they might add center or center & rear speakers to give the surround effect, then finally add the Sub.
In terms of price, I think you will find that the Sub, especially a good one, is the most expensive piece.
Next, are you going to mix and match, or go with all one brand. Usually, mixing and matching speakers from different manufacturers is not recommended unless you have a lot of experience with a variety of speakers and really know what you want.
You could scan through various 5.1 systems that you think you might eventually be able to afford, and simply start trying to duplicate them a few speakers at a time.
Or you could start with a good set of rear speakers, actually just bookshelf speakers, and use them for Fronts. Then when you are sitting on a pile of money update to larger matching bookshelf or floor standing speakers. Move the old fronts to the rear, and move the new larger speakers into the front.
Ultimately, you will, without question, get more in the end if you upgrade a piece at a time.
But, in the mean time, you have a 5.1 or 7.1 amp sitting on the shelf with most of the channels going unused. And, by the time you are ready to upgrade, will simply adding a couple speakers be enough, or will you at that time, just want to chuck it all and start over with an all new system?
In a sense, it depends on how fast the money is going to come. If you can finish it off in a year or two, then it might be OK to upgrade a piece at a time. But if it goes beyond that, I think you are probably better off buying a whole small system now, and when money is better in the future, just replace the whole speaker systems.
One possibility is to buy a cheap 5.1 speaker system now, then when money is better, add a really nice set of front speakers, and set it all up as a 7.1 system. The center and rear speakers usually aren't working that hard, so they are not as critical as the fronts and Sub.
You could then gradually replace various speaker in the system to match your new fronts.
For example, using speakers at random, you could start with the Jamo. Then when you had a spare £150 to £200, you could move Wharfedale 9.1 or 9.2 to the front (or Kef, Q Acoustic, Quad, Kef, MS, etc...). Now you have a pretty sweet 7.1 system. Later, you could swap out the cheap center with a better matching Wharfedale center (or other). That would improve the dialog. Next, when the money is right, swap in a righteous Sub, and now you really have a sweet sounding system.
So, at this point you probably have a system that you have no complaints about. That should, at that stage, be a very pleasing system. Then when the mood and the money strike you, you could finally swap out the Rear speakers.
Using this method, I wouldn't be too concerned about mixing and matching. Mixing the Jamo's with Quad, Kef, or Wharfedale is not a problem. But when you start swapping in new speakers, try to keep them all the same brand. The one exception might be the Sub, though at your budget level, keeping the same brand might be best. But, if you suddenly hit a ground swell of free cash, there are a few subs that stand out, though they are probably going to cost about £400 or more.
Starting with a good pair of £150 to £200 fronts is ultimately going to lead to about a £500 to £700 speaker system. You need to consider how fast you can come up with that kind of cash. Like I said, if you can pull it off in a year or two, then this might be the route to take.
But if you aren't sure how fast the money is going to come, then buying a full 5.1 cheap system, and gradually upgrading it might be a better choice.
Ultimately, it is up to your and your cash flow to determine.
steve/bluewizard