In the UK, there are four main types of Consumer Unit:

Main Switch Consumer Unit – Offers highest degree of circuit separation as all circuits must be protected from earth leakage independently. This can also be an expensive solution as it necessarily uses RCBOs instead of MCBs

Dual RCD Consumer Unit – Offers a cost effective solution to meet 17th Edition Regulations by protecting two banks of circuits from earth leakage through the use of two RCDs

High Integrity Consumer Unit – Usually used in larger properties with greater numbers of circuits, this type of consumer unit offers good circuit separation through the use of two or more RCDs whilst allowing for the independent use of RCBOs. Usually this type of consumer unit also allows for fully flexible configuration, meaning there is no restriction on the number of RCBOs used

RCD Incomer Consumer Unit. Less common than the other types, an RCD incomer does not use a main switch. They are usually used as a sub-board to a main distribution panel

Modern consumer units usually use DIN-rail mount breakers. The rail and the shape of the front opening are standardized but the busbar arrangements are not. Therefore mixing of brands should generally be avoided and, where unavoidable, care should be taken to ensure that the breaker chosen is a good fit for the busbars.

Generally a “split load” arrangement is used with some circuits protected by the RCD and others not.

If you have a fuse board with re-wireable fuses then you should seriously consider having this upgraded.