Hi Raj, 

Theres quite a few out there...MS marquees? Some of the madap and decor companies also have good contacts. The cost is usually a fixed price for the few days you need it for. They know that you want it for more than one day - typically a week, so charge accordingly. Based on my experience, the price range is from £500 - £1000, depending on quality and size. They usually provide tables and chairs, and interior decorating too for that price. Hope that helps !