Short answer is Yes. As the owner of a rental property you have the right to sell your house. It does not matter if the tenant has a fixed term tenancy. The new owner will however have to honour the tenancy if it is a fixed term tenancy with time to run to the end.
There are a few laws around showing prospective buyers through the property. Correct notice needs to be given (it is not a stipulated period) by the owner and you cannot insist on open home viewings. There are laws governing the tenant as well - such as they cannot unreasonably withhold their permission for prospective purchasers to be shown through.
In all things communication is key. Keep your tenant happy and informed and you are far more likely to get co-operation and a nicely presented home. A good property manager should have excellent diplomacy and negotiating skills.