Re: does the landlord refund you all the money you gave to pay the rent?
Within the limits of that analogy, wouldn't it be more like not being refunded for the new bathroom you fitted?
In the UK, a tenant doesn't get any recognition for improvements to a house or flat. Though a tenant might get charged for any alterations. And improving a place means means it's worth more, so expect the rent to rise. Even if you have a landlord who would naturally play fair, they'll have to have the strength to stand up to the agent who recommends the higher rent for the improvements.