Think the legalities have been covered, i.e. its your land and its therefore your choice. You are not in public on your land so your not carrying a RIF/IF in public. I cant speak for your force, but if you are taking reasonable precautions I doubt there will be much interest there. You could just as easily be shooting rabbits or anything else, again private land, your call.
Something you may want to consider is opening up to other local skirmishers (at your invitation or course) assuming you have met any. A few peeps can have fun, but 10 can have more

Obviously then you may want to look at some form of 3rd party insurance for your own protection in case someone was hurt while playing.
Also playing on your own land wont count towards a UKARA / Defence as you dont have 3rd party insurance. Not that I would let that stop you, I wish I had enough space to host small games as most of my mates would love to pop out for a 45 min skirmish and on to the pub every now and then.
Weapon wise its very much a personal thing, obviously anything can be 2 tone as most suppliers will happily paint for you. A decent weapon is worth the extra over a very 'budget' gun for range an accuracy. Personally I have had some very good rifles in the £100 - £140 price range, mostly second hand. Most of the insides are the same between AK, M4, etc. if they are similar price wise, only when you start going more expensive do you get better internals. So just decide which you like looks wise the best. Or of course you can do one of each.
I would suggest a quick google on any make you plan to buy, check you can find some reviews and instructions to dissemble in case you need to. See if you can find parts or spares. All useful to know what your options are before you buy it, rather than finding out should it break you have no options to fix
Transparent if you going 2 tone I personally think works better than bright orange / green, if you buying a dedicated 2 tone. Works even better in the snow, my first was a clear M4 very much like the suggested one of CraigW-H. Then again blue isn't that bad either, I just have a hatred of orange
These guys have a 'Professional' 2 tone section, cant vouch for them but at least it gives some examples of what is out there. Good luck on your hunting.
http://www.actionhob...AEG_B22C48.aspx