'good leasehold'

Hi, I have recently purchased a property which is listed with land registry as good leasehold', the garden area is listed with a possessory title separately, and there is a piece of land at the back/side of the property which has been used and gated by the previous occupants for the past 8 years. Our solicitor informed us when we purchased that we could apply for the good leasehold to be upgraded to 'absolute leasehold, we could apply for the possessory title to be upgraded to 'good leasehold' for the garden and the untitled area we would be able to apply for our own possessory title for. We have a statutory declaration from the previous owner stating that they gated this area 8 years ago. My question is, can we do all these ourselves? Our do we need to appoint a solicitor? I consider myself quite knowledgeable about the situation so am reluctant to pay if it is just a case of form filling. Any advice greatfully appreciated.