As previous post have mentioned an EICR (electrical installation condition report). This will flag up most issues and recommendation on any remedial work or updates required. Only then will know what upheaval will be required as not all installation are suitable for a straight swap over and a EICR would help identify any inherent issues and hopefully prevent any attributed power loss in the future.
The EICR will require access to the existing fuse board, the metering, the earthing conductor, main earth bonding clamps, any supplementary bonding, switches, sockets, light fittings, outlet plates, isolators, fused connections, accessible joint/junctions etc.... So would be very helpful to the electrician if you are familiar with the positioning of these and they are accessible.
Also as your existing wiring to the existing fuse board could well short in length and require extending, sometimes this can be done within the new board, sometimes external of the new board or sometimes if more practicable a new length fitted and don't rule out the need for new tails, earthing conductor and main earth bonding to be updated.