Like mac said keep your springer , you might be able to find a regged BSA ultra for about £300 which will give you about 55-60 shots with no power curve, very good gun
If you can find About £800 you can get a good second hand HW100k set up including scope , bottle , bag , sling, in ether .177 or .22
AA pcp another good gun , but imo the ultra is a bit better
If you do go with .177 you can use light or heavy pellet for hunting ,depends which pellet is the best for your gun , My ultra likes JSB Heavies 10.3gr and the HW100k likes 7.9gr JSB express ,even at 60 yards, both are thes