ok, out of those options, get this lot:
gun:
http://www.zerooneairsoft.com/product_info.php?cPath=268_318_403_494&products_id=5774
Excellent starter gun, will shoot just as far an just as fast as almost any other gun. The internals are rock solid and will put up with years of use (not ABuse though!).
Battery:
http://www.fire-support.co.uk/product/vapex-74v-1450mah-25c-lipo-battery-cranestock-airsot-rechargeable
LiPo is the future, no point buying a NiMh and charger now and then in 6 months deciding you want to go LiPo (and you will).. that said, 11.1v will put more strain on your gearbox and make your gun die sooner than it would have otherwise so stick with 7.4 to begin with! You may also want one of these:
http://www.fire-support.co.uk/product/kong-power-lipo-alarm-111v-and-74v-connectors-included to let you know when you're getting a little low on juice, there are others on the market so have a look around and find one that fits with what you want.
Charger:
http://www.fire-support.co.uk/product/kong-power-battery-charger-support-for-lipo-life-li-ion-nicd-nimh
Not the most feature laden charger in the world, but they work and they're relatively cheap!
Sights:
The iron sights that come with the gun will be more than enough, buying flip-up backup sights is just for looks really, if you really want to spend out on them go for it, if not don't bother! Replica EOTech and aimpoint sights etc can be had for very little on eBay and they're all as good/bad as each other, on an airsoft gun even the worst/cheapest red dot is more than good enough. Again, these are just an affectation really.
Other stuff:
Magazines... you can go 2 ways with this initially, you can go all out and buy a load of mid-capactity magazines (these don't need winding and don't rattle) but then you'll need a way to carry them all... more expense! Or, you can buy a couple of high-capactity magazines for much less money, have one in the gun and another full one in your pocket.with 2 high-caps you'll be able to carry 600+ shots in magazines and then just have a bag of loose ammo in case that's not enough.
http://www.fire-support.co.uk/product/socom-gear-noveske-licenced-450rd-m4-hicap-magazine-grey those will do you nicely!
Hope that's helped!
Alternately if you want to go nuts, get this lot:
http://www.fire-support.co.uk/product/systema-ptw-training-weapon-m4-a1-max2-m90-2012
http://www.fire-support.co.uk/product/kong-power-1300mah-20c-111v-stick-single-pack-lipo-buffer-tube-battery
http://www.fire-support.co.uk/product/magpul-pts-pmag-systema-ptw-magazine-black
http://www.tactical-kit.co.uk/eotech-exps3-0-night-vison-compatible-holographic-weapon-sight-10515-p.asp
But bear in mind, that gun won't shoot much further than the G&G Combat Machine... it's still shooting 6mm plastic balls at no more than ~350fps!