There are many options, when my mother lost her leg, and the kitchen needed redoing, the whole house needed a rewire. Dad would not allow it, so had to find a workaround, what we did was have a 40 amp MCB in the existing consumer unit (CU) feed a small new CU in the kitchen using SWA cable, so that cable did not need RCD protection, and have RCBO's in the mini CU in kitchen.
Be it Ali-tube or SWA there are cables which do not need RCD protection. So someone has to look at what you have, and design a system to get around the problems, and he will sign the installation certificate where it says design, also someone needs to do the work, and they sign they have installed, and someone inspects and tests, and they sign for that.
However, most of the scheme providers don't use multi signature installation certificates, so one person has to do it all, however, they still have to do the design. We can't design it on a forum, it has to be done by someone on site.
The CU you show is no longer suitable, it will need changing, if for no other reason it would be hard to get any parts to fit it. The consumer unit is a type tested distribution unit, and to retain the type testing, you can only use parts which the manufacturer have included in the type testing.
At the end of 2021 Kempston Controls announced its acquisition of MEM (Midland Electrical Manufacturing). The deal includes Eaton’s Memshield I & II ranges of circuit protection devices and also the Cutler Hammer DC crane controls.
so it is unlikely you can get new parts for that box, that are permitted to be fitted. So not real option but to renew it.
However, likely it will be cheaper to renew it anyway, as obsolete stock can be very expensive to get, and also unlikely you can get type A RCD's or RCBO's for that box, so you need to find a scheme member electrician to design what is going to be used, I would go for a firm rather than one-man band, as last thing you want is for an electrician to be ill at a crural moment.
