It's probably around 30 years old.
It's a metalclad, and has the original RCD so, by the standards of the time, it was probably a better quality installation than average.
But times have moved on, and @flameport
makes correct points. Save up for an all-round modernisation.
In the past, I have had a similar ones with the MCBs, and it was more convenient on the very rare occasions that an electric iron had a flex that wore out and shorted (I don't remember any other fault that caused a trip*), and in those days, inspection reports would often say that rewireable fuses were unsuitable (because they didn't trust users not to use thick wire, as happened in your home). Cartridge fuses are inconvenient because householders seldom have a spare set of new ones and are tempted to make dangerous bodges.
If there is any risk that some numbskull might make a bodge with a bit of wire again, MCBs will probably avoid it.
Note also that your RCD is rated at 63A max for the whole house, so if you have an electric shower and some electric heaters or an electric cooker, it might be overloaded and damaged. As far as I can see your CU was built for max 30A/32A fuses/MCBs so it was not designed for an electric shower with a load greater than 7.5kW, and a modern electric shower will typically need more than that. Hence your fuse blowing and the contacts being overheated. Another factor driving you towards a rewire. If funds are short, you could start by upgrading the shower circuit and putting it as the only circuit in a new, additional CU with space for other circuits to be migrated later.
*although in those days, the old incandescent "filament" bulbs could cause the lighting circuits to trip, especially if it was a spotlight.