with that budget you can buy an ultra and have it tuned/regged this guy does a good deal on bsa's i think ultra is about £280 ish http://www.classicmilitaryarms.co.uk/
aahhh the good old not so sweet 16 i used to have one but was warned you had to use it as if you meant it i found once i got the hang of hitting it hard with the palm of my hand to load it it worked ok
like the op said only ever clean your barrel if you have accuracy problems or if you buy a second hand rifle and dont know what pellet was being used, even then it will take a few pellets to "lead" back in