Even so the price seems massively excessive.
That's because it is, it's twice the price I'd expect up here for that type of property.
We pay about £3k for a 2 bed house and that's using a sub contractor where the main contractor has put a little on top for themselves.
I'd be looking at paying no more than £3k taking into account current cable prices, as they will need to go up a size on cable due to the installation method likely to be used.
£5k is eyes out money imo, I'd expect something like that for a 4 bed house with garage for example.
Further south it's probably about right.