I am looking for a hotel in Amsterdam, for around £150 a night or less. It MUST have a hot tub/jacuzzi in the hotel room. It needs to be as close to the centre as possible. It would be an advantage if it had a swimming pool, nice bar etc... Any suggestions??
The Hotel Roemer, Roemer Visscherstraat 8-10, just completed an expansion in an out building which added twelve deluxe rooms. The so-called 'Junior Suite' contains a jacuzzi, there's an image here.
The Trip Advisor site has a page called the 20 Best Amsterdam Hotels with Jacuzzi.
Comments have suggested that you can also accomplish a basic Google search. If you want to search for more, these are the 5 star hotels in Amsterdam...
Source: "Hello Amsterdam" magazine, Sep/Oct 2015, issue #4, published by http://helloamsterdam.nl/en/
The room prices at these hotels will require flexibility with your GBP 150 budget, but the final price will depend upon the arrangements you make with the hotel, your credentials, and so on. I cannot list their prices here because they are massively volatile and season dependent and you did not provide that information in your question.