I'd recommend checking out Bathstore or Victoria Plum. They both offer a range of options that might give you a good basis for comparison.

Clapham park Bathrooms is brilliant. Very helpful, range for all budgets and a good showroom
It’s on the corner of Clapham park Road and Bedford Road

Bathrooms at Source in Earlsfield is also great. Bigger showroom but gets quite busy so you might be waiting a while to speak to someone

Burge and Gunson in Colliers Wood have a huge showroom and reasonably priced products. They can do the design for you as well.

CP Hart in Waterloo is a great place to go for inspiration. Not the cheapest but you don't have to buy everything from them! 

Desperately in need of an updated shower room. Could anyone suggest somewhere other than West One Bathrooms that I could go to for shower furniture / appliances. I do like their offering but would love to be able to compare with another brand. Thanks!