You should have been given a copy of your lease by your solicitor when you purchased your home, but here are other ways to get a copy of your lease:
Apply at the Land Registry - The quickest and easiest way to get a copy of your lease is from the Land Registry. The cost is £7 as of July 2016. You'll need to download form OC2 from the Land Registry website and send the completed form (with a cheque for payment) to the Land Registry office that deals with your property. You can also contact the Land Registry directly on 0844 892 1111.
Contact your solicitor - The solicitor who handled the purchase of your property can arrange a copy of your lease for you. It's likely your solicitor will charge you an administration fee for this service.
Contact your mortgage provider - If you have a mortgage provider, they should hold a copy of your lease and should be able to send it to you for a fee.
Contact your PMO using My Account - Your property management officer (PMO) can arrange for you to receive a copy of your lease. He/she may need to order a copy from Land Registry. The fee for providing this service to homeowners is £48 (including VAT).