Those are probably the easiest choices, you can take the H'Ex for free to T123 station and walk from there. If you want a lot less space at a lot less money, there is also the Yotel in T4.

You can also consider the Hilton at Paddington and take the H'Ex in the morning -- it will be about as fast as connecting from T4 or T5 -- and allows you to spend the evening in London.