It is a retail internal repair lease 3 years long duration. The lease ended up in April 2013 and Rolling over as a quarterly periodic tenancy.
Notice provisions and how notices are to be served are usually contained in the lease. If the lease is silent in that respect, then they should be in writing but don’t need to be served by a solicitor. Email is not generally considered to be sufficient.
There is no central record of notices and a three-year lease does not need to be registered at the land registry
Can I clarify anything else ?
If there is no provision in the lease then it should be served in writing by first class post although to make sure that the person cannot deny they got it, obtain proof of posting from the post office counter.
Legally, provided you can prove that you posted it and it’s not been returned to sender as undelivered then the Postal Service is deemed to be 100% reliable.
That is sufficient purposes. I would send it to the tenants private address property address and if it’s a limited company, to the registered office address