""the consumer units to both the house and garage are dated, there is a general lack of visible cross bonding throughout and unclipped wiring to the garage""
It means he thinks it looks old but he isn't competent to test it (and wasn't paid to)
What he mentions is trivial
"cross bonding" might mean Supplementary Bonding in the bathroom, but he probably also means Main Bonds to your gas and electricity pipes. This is an important safety feature but luckily is not difficult or complicated, an electrician could probably do it in half a day (may be difficult if the pipes enter the building a long way from your meter and there is no easy route). It would have to be done before any future electrical work. Cable clips cost about 50p a hundred so the electrician could easily do that while his tea cools.
If the electrical installation is generally old (it sounds it) then it probably has insufficient sockets for modern needs, and there may be invisible defects that no longer meet current standards, such as no earth in lighting circuit, and no RCD protection against electric shock. If you need to have it rewired, this is best done before you spend all your money on redecorating and carpets.
I wouldn't bother paying for an electrical survey unless you actually buy the thing. Just assume that it will soon need rewiring, and since the age and condition is pretty obvious, the vendors will say they have already taken it into account when setting the price.
Rewiring a house costs the same as buying a secondhand car.
You'll need a properly qualified electrician when the time comes, a member of one of the Competent Person schemes such as example
Look for one who's been in business a few years, and is local, and is not just a "Domestic Installer" (which is the lowest grade).