£250 way too low.
Labour 1.5 days x £150 = £225
Addy x 2 spf @ £20 a bag = £40
Chrome trim @ £10 each = £20
Grout £10
That's £295
Was your full day 08:00 - 16:00? or maybe a bit longer??? - if so, then add on a few extra for the extra hours worked.
In my view 12mtrs in a day is pretty fast (you should be charging extra for that skill).
Cheers
Sean