OP has the electrician added lots of "extras" you don't need such as 5amp plugs and CAT6 cabling??
And has he added expensive face plates ie ones that are not white plastic?
Is a new security alarm included?
£10k sounds a little high but it depends very much on what is included.
I'm paying £20k+ vat to rewire an 8 bed house inc upgrade of supply to 3 phase and electric UFH in 3 bathrooms plus exterior lighting.
There is approx 300 points in the house - a "point" being a socket, light switch, a light, downlight or bathroom fan, oven etc you get the idea.
That means I am paying approx £66+ vat per point.
Count up all your points and divide. If you're paying more that £75+vat per point, I would question it.
If you're paying £75 or less, then you need to scale back on the stuff you want to put in or you won't get the price down.