I hired one from Birth Pools Online link here
Really couldn't recommend them enough.
They're in Essex /East London area, courier delivery or collection or option to pickup for cheaper. I picked mine up and had it for 6 weeks for £245.
They're 5ft by 5ft, quick and easy to set up, not inflatable, heated and easy to set temperature, come with 2 brand new filters, disinfectant spa tablets, clothes, dettol spray, mirror, torch, hoses to fill and empty, waterproof tarp, soft foam edging, lining, fast pump to empty.
I loved floating about in it during the evenings on maternity leave, to take the weight off and relax my hips. I used the provided disinfectant tablets daily and only had to change the water twice while I had it - which was quick and simple enough.
The company seem flexible if you need it for a bit longer and didn't charge me anything extra.