Do I need to upgrade my old fuse box to rent out my property legally

You have a legal duty to ensure the electrical installation is safe. This does not mean that the consumer unit as to comply with the latest regulations but there will be a minimum requirement. Get a ECIR done by a registered electrician on the installation and act on any recommendations made

Only if it fails an eicr

Yeah as per building regulations and renting laws, you need to have an up to date RCD protected main consumer unit and interlinked smoke alarms throughout your property. For any further information consult a qualified electrician and I would be more than happy to help

The Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020 requires landlords to have regular inspections of their properties electrical installation. There is a 5 year limit on the interval. This can be satisfied with an electrical inspection and condition report (EICR). If carried out correctly, the report will flag unsafe findings and give a list of observations with codes advising of remedial actions required. Upgrading a consumer unit just because it is 'old' or not to latest Regulations is not a requirement and should not prevent a property from being rented.

Yes if renting out a property you should always have the latest board with RCD protection, after board change you should have an EICR carried out on the property to check all wiring

Best is to get EICR done