The lease should contain a provision specifying how notices under the lease should be served. If in doubt, send to everyone by every possible means well in advance and ask them to acknowledge receipt. Section 48 of the Landlord and Tenant Act 1987 requires the landlord to notify the tenant of the address for service of notices, and the tenancy agreement will almost certainly specify this.
The lease should contain a provision specifying how notices under the lease should be served. If in doubt, send to everyone by every possible means well in advance and ask them to acknowledge receipt. Section 48 of the Landlord and Tenant Act 1987 requires the landlord to notify the tenant of the address for service of notices, and the tenancy agreement will almost certainly specify this.