thankyou, it was completely fine until it had the cassette and chain changed. Also if i give a hard push as you said a couple of times it doesn't pedal backwards and for some reaseon it feels tighter now then it did a couple of days ago before i had the cassette changed.
ever since I've taken my bike to the shop to get the cassette replaced the chain now moves when i pedal backwards , unsure if its anything to worry about ?