The installation has passed a recent EICR done by the seller but
Further information regarding satisfactory or unsatisfactory EICR's..
There is a free PDF donwload industry recognised best practice guide for EICR's
https://www.electricalsafetyfirst.org.uk/media/mi1oqkur/best-practice-guide-4-issue-7-1.pdf
This gives examples of typical reporting codes.. (C1, C2, C3 etc..)
bottom of page 17 it suggests that a CU with missing blanks is a code C2..
An EICR with any C1 or C2 code cannot be considered satisfactory.. So if someone has issued a satisfactory report for the CU in your photograph then they probably lack sufficient competence to carry out accurate inspection and testing of electrical installations?
Also if someone has recently undertaken inspection and testing, there should be a durable label on the CU stating last inspection date and recommended next inspection date!
e.g. something like..
I cannot see one in your photo?
(There should also be a label regarding checking operation of RCD's by their test button..)
These labels should have been fitted.. (along with accurate circuit descriptions) .. By whoever installed the CU.. And if they are not there, I would have expected the person undertaking an EICR to fit them..
Because labelling and identification of circuits / consumers units is such basic easy stuff..
If I ever find installations where they have been omitted... I generally suspect that some of the more complex design, installation, testing, aspects may also have had corners cut, (e.g. omitting some 'dead' and/or 'live' tests on the amended circuit).. so although a circuit may be working.. it possibly may not disconnect the supply fast enough in the event of a fault to protect from risks of fire/shock etc..
Also.. a consumer unit cover is a nice free advertising space for any reputable electrical contractor.. And if you have done any BS7671 compliant work you are proud of.. Why would you not put a label with your name/contact no/website etc.. on the front of the CU??
I know I do!!!!
That CU photo suggests no competent electrician wants to be identified with the installation..?? Which in my experience indicates there are some issues of concern that they do not want to be associated with!
So I would recommend getting a new EICR undertaken...
Or..
Just get an electrician to install a new full RCBO metal CU with surge protection, (plus your new shower circuit), and issue a new EIC and Part-P compliance notification..
P.S.
I can't believe anyone would fit an RCBO doing nothing..????
And yet fail to label up the CU as to what it actually does do??
This installation may not be a 'can-of-worms' but it could still be a few dirty laundry baskets needing tiding up and sorting to get it all neater and functional to a satisfactory standard!
P.P.S
back to your original "plastic CU" question..
bottom of page 22 of the guide it does suggest that in some circumstances it is not even worth a comment on an EICR!!
Hence earlier comment regarding competence of this "Sellers EICR"...
It could be wise to get your own inspection undertaken?