I put a shower + bath and retiled my tenement bathroom. the bath was \~£250, shower fittings \~£300, tiles \~£300, tiling \~£200, joiner (new studs and hardyback) was \~£250 and plumber \~£300 if I remember, shower door \~£150
The bath one a cheap one, shower fittings fairly nice ones. I am probably forgetting a few things but I yeh £8k sounds like an awful lot to me