Back to the original question.
A bottle jack will certainly do the job, is the lightest option, and the cheapest. But it can be difficult to place, and more unstable in less than ideal conditions.
A trolley jack is heavier to lift out of the vehicle, but easier to position, as it is on wheels and can be shoved around by the handle. Of course it takes up more room in the vehicle.
Go into Halfords and have a look at the options, see what they weigh and how big they are. Check that they have enough lift to raise you vehicle.
If you are worrying about the weight of things, however, the weight of the wheel may be your biggest problem. Try lifting the spare down and see what I mean. Worse than that is when you are trying to put it on the studs and have to lift it quite precisely. Try it out on the drive before you have to do it for real.
I don't know how well the impact driver will work (again, try it out now), but I like to have a socket and a good long arm to lever it with, say 3ft, not the little ones in socket sets.
Also have in your kit a small tarpaulin to lie on, perhaps a kneeling pad, gloves, wipes for removing mud and oil from yourself, and one of the plastic covers garages put over the seat to keep it clean.
In case all that fails - pack the lap-dancing kit. Guaranteed to get the wheel changed almost instantly!