There is a hotel attached to T5 but it is very expensive. I would recommend the Premier inn Bath Road, its about a 10 min drive from T5 or you can use the airport hoppa which I think is about £6pp, booked in advance you can easily get it under £50, the restaurant there is quite good value as well and there's a good breakfast.
You cant go wrong with most of the hotels on Bath Road to be honest, but I think the PI offers the best value.