Technically you are under no obligation to use a solicitor. However, if you are taking out a mortgage, your lender will usually insist that a solicitor be used for the conveyancing.
Conveyancing is much more complicated than most people think. Your property solicitor will deal with all the legal elements of the transaction (of which there are many). It’s not just about filling in forms – there are many searches and formal enquiries that must be made before a transaction can safely take place. Without professional input from a qualified solicitor or conveyancer, there is a high risk of serious problems arising. For example, if something does go wrong, you’ll have no cover. If you use a professional, you’ll be fully covered by their insurance in the unlikely event that anything goes wrong.
It’s worth remembering that this is probably the biggest financial transaction of your life, so you do need to have confidence that the legal and financial aspects are dealt with properly.