I think it will vary from company to company, I am not sure you will need to meet HR, more likely this will be your Manager. It is likely that there will be some assessment done after the 6 months given to you, however this may not happen.
Also you may not need to sign another contract as it may be in the original one but you should get some confirmation that you have passed your probationary period and are now a permanent member of staff. Best thing is to ask HR or someone else in the company how does it generally work.