A typical England & Wales purchase runs: instruction and ID checks, draft contract and title from the seller's side, local-authority, water/drainage and environmental searches, pre-contract enquiries, mortgage offer, then exchange of contracts (the point it becomes binding) and finally completion, when funds move and keys are released.
The conveyancer's core job is to confirm the seller can sell what they are selling, that the title is good, that nothing in the searches or lease undermines value, and that the buyer's money and any lender's charge are protected. On leasehold they review the lease term, ground rent, service-charge accounts and any management disputes.
After completion the conveyancer pays SDLT and registers the buyer as proprietor at HM Land Registry. Delays usually come from slow searches, leasehold management packs, or a long chain — not the drafting itself.