I've also checked out the Air Arms S200 (also called the CZ 200 S over here apparently) and that one is a fair bit more at about £305 but you also need a pump for it right? and then a scope too. I don't really have a set budget and the price isn't a problem it's just that I may not use it that much so don't want to spend loads initially, we'll see though
I'm also not sure what calibre to go for, my understanding is that the 4.5mm (.177) being a lighter pellet than the 5.5mm (.22) is faster and has a flatter trajectory. Also they should both have the same energy right? as energy stored in the gun and transferred to the pellet is equal, but I'm guessing the .22 suffers from more drag and will lose energy quicker.
PCP´s are great ,but if you go down that road instead of a pump (they are expensive (around £100/150),also they have some parts that need to be replaced time after time ,and after every 40/50 shots you need to fill the gun again( for example I shoot around 40/50 pellets a day,so in my case it´s like to go to the Gym everyday
)
the better choice for a PCP is to have a divers bottle ( normally at 200 bar)of 6 / 10 litter,with a quick fill connector,so in a few seconds you have your gun ready again,without all the hassle of a manual pump
the 6 litter one gives you around 1000/1200 shots
here in my country,when we need to get the divers bottle filled,we went to the firemen station,they fill it up( the 10 litters one) for 2.5 euros
about the caliber- I have the .177 because it is cheaper than the .22( I use JSB exacts 4.52)I spend 2/3 thins of 500 a month (around 18 euros )
if it was the .22 it costs me the double
with a 12 ft/lbs gun( the legal limit of the UK),that´s right the trajectory of the .177 is flatter than the one of .22
but with a gun of 30 ft/lbs or more, you do not need to worry about the trajectory of a .22 pellet,it will be very flat
the choice depend of the objective you are going to use the air rifle.
I will, give you my example.
with my HW97k ( FAC power,around 17 ft/lbs) .177, I easily kill sparrows at 50/55 yards,if I hit them , they are dead;
but a bigger bird like a feral dove ( they are a little smaller than pigeons) at 30 yards,if it was hit at the head,neck or in the chest,they drop right away;
but when i hit it at the back or in the side,most of the the times they flew away (sometimes they left a lot of the fetters behind,but nevertheless they are still healthy enough to get away)
if my gun was a 25/30 ft/lbs .22, I´m sure they stay dead in the spot
the .22 calibre has much more energy in it than the .177,after all it has the double of the mass and weight
I recommend you to read that basic guide from that air gun store - BAR( Blackpool Air Rifles),they are great experts and very professional
I think that guide is very helpful
http://www.airgunbuyer.com/page.asp?pg=18