New car faults

Hello all. I've recently purchased a mk2 vrs (petrol) after my mk1 was written off. But with most cars there's some little faults with it so I need your help. The car runs fine but it's lumpy on idle. There's no faults on a code reader. I've had a look on other forums and it points to it being the pcv,but wouldn't this throw up a code? I've also tried to have a look but I can't get the plastic cover off is there a nack to this? Lastly I went to get the aircon recharged but was told there's a leak around the compressor. Would I need to get this serviced to check for cracked seals. If anyone knows where I can get this done around the portsmouth area. Thanks for reading and any help will be appreciated.