I sold a house last year and the solicitor left it up to me to sort out the CGT, which is as far as I'm aware the correct way to do it. Depending on the date you sold the house, I think you may have up to nearly a year before the CGT deadline, and would be better off with the money in the bank for those months and waiting to pay the CGT at the last minute before the deadline.
And are you non-resident? Which is the relevant point in case you missed that bit.