'Working from Home' - How do you charge your company for Telephone/Broadband?

[ASC1951]

I'm self employed. I just give my accountant the figure for my total phone and broadband use (both with Plusnet) and my mobile bills and he agrees an apportionment with HMRC. I've never been asked to do a detailed calculation and IIRC there is a going rate for this. I also claim £600 a year for 'use of home as office', which again I think is fairly standard.