Hi Jan,
Not sure if you need parking aswell but myself and some others got an excellent deal the week before (£62 or something like that) for the Park Inn and a weeks car parking at the hotel.
Got the deal through holiday extras by taking the "undercover 4 star hotel" deal. You are not supposed to know which hotel but could work it out because they named the "bravo brova restaurant" in the more info section.
Its not near terminal 5 (only a couple are actually at the terminal) but you can get the 423 service bus across the road from the hotel which is free (heathrow freeflow zone), only takes 10 mins and they run regular, actually quicker than the hoppa buses you pay for.
Nice pub for evening meal opposite the hotel called "the 3 magpies" few of us are meeting there the night before our Slovenia holiday.
Mick