Verbal or written contract

Does it make a difference if I have a verbal or written contract?

There is no legal difference between a written or a verbal contract. In law a contract is a contract.

However, if there is a dispute it clearly helps to have something in writing in order to verify what was agreed.

Some types of letting also require the service of notice in writing and cannot be created verbally.

For instance, if your verbally agreed an Assured Shorthold Tenancy, which commenced before 28th February 1997 and there was no written notice, then in fact it is an Assured Tenancy.