Quick answer
If you have old rewireable fuses, no RCD protection, or a plastic consumer unit fitted before 2016, upgrading is strongly recommended.
You do not legally have to upgrade your fuse box unless you are having electrical work done. However, there are clear signs that an upgrade is advisable: old-style fuse wire rather than modern circuit breakers; no RCD protection (no switch marked RCD or the big switches in your consumer unit); a plastic consumer unit fitted before 2016; the consumer unit is over 25 years old; an EICR report has recommended it; or you are adding a new circuit for an EV charger, solar panels, or an extension. A modern consumer unit costs between £500 and £1,000 installed and provides significantly better protection for your home and family.
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