P800 - requested refund by cheque

Good afternoon, Today I have requested my p800 refund to be refunded by cheque, it says I should receive the cheque by 28th August. Is the likelihood of it coming any sooner possible?? as I go on holiday on the 28th and that cheque would be very much appreciated. Is the 6 weeks the time frame for it to be issued or does that include the time in the post to be received by then. Thank you in advance.

Hi,
You should receive your cheque within 6 weeks from the date this was requested, this could be sooner than the 6 week timescale but cannot be guaranteed. 
Thank you.