I think the Jamos are definitely limiting both systems. I think I'd try and split the cost between the Blu-Ray player, the AV amp and the speakers more fairly. So, let's assume you go for the Panny TV (good choice I think), this leaves £1,180 for the rest. Personally, I'd spend the most on the speakers, then split the rest between the Blu-Ray player and the amp.
For me, the
Q Acoustics 1010i 5.1 package is brilliant value at £450 (NB - possibly cheaper elsewhere, I've not done any thorough searching during this). It's a more traditional system to the style package which may be a problem for you, but if you can fit them in, this is really worth it as the sound will be much improved over a style package.
This leaves £730, so my next step would to spend about £400 or less on one of the new AV amps like the
Onkyo 606 or the
Yamaha 763, or indeed the Sony 2400 you mention above. To be honest, there's a lot of choice on amps at this price level and I'm not familiar with most of them so I recommend auditioning where possible and checking out the WHF Awards Issue on Thursday for more help here.
So, with no more than £400 spent, this leaves £330 for the Blu-Ray player. You already have the Sony BDP-S550 up there at £300 so this fits in nicely here, but you could also look at
Panasonic DMP-BD35 or even Sony's cheaper
BDP-S350. The reason for the inclusion of the later is, with the one of the amps above, you'll have no need for the decoding abilities aboard the Blu-Ray player and also, you haven't mentioned speaker stands or cables which you also need to account for. Saving some money here could therefore go towards that fund.
Those are my thoughts, feel free to come back with any questions - I guess the main thing I would do before buying any of the above is go and check it out in the flesh and my thoughts would probably flow from there.