Those Toolstation ones are 1.8 watts. But I've seen 3 Watt versions in Amazon for around £7 each. But note that any GU10 lamp (obviously) will require light fittings with GU10 holders.
Your picture shows you've got a perfect, plain and light coloured wall which would lend itself well to a bit of colour behind the TV.
Red, green and blue mounted out of sight behind the TV and firing up the wall would be effective, especially after experimenting with overlapping beams.
Having said that, I put 3 whites behind my Dad's wall mounted TV, all just firing directly upward and they looked great.
I screwed 3 of these to a wooden batten:
http://cpc.farnell.com/unbranded/3423/gu10-lampholder-with-pvc-cable/dp/LP10008?st=GU10%20holder
Alternatively, although their beams wouldn't overlap, you could always put coloured bulbs (of the appropriate type for the holders) in some, or all of your uplighters - unless these are your only room lights that must remain white.
Dont forget that there are now quite a few versions of LED bulb that can have their colours selected by (supplied) remote controls or apps. Whatever you do though gel, be safe - maybe stick to low voltage LED strips - or don't bother!