OO it is your money you can do with it what you want. Just make sure you arrange your mortage so there isn't any shortfall.
If some costs are estimates it can be worthwhile arranging a slightly larger mortage than you feel you will need, draw that down and once you have paid everything that is due you can than make a lump sum payment into your mortage with what you have left. You need to be good and make the payment of course and ensure there are no penalties attached to lump sum payments. (Most high street deals will allow at least 10% in one year without any penalties now thou'.)