OK, my niece has asked me to do this

and really I want UK plumbers.
How much would it be for a replacement hot water cylinder, new central heating pump and new water valve box inc labour etc?
I haven't got a clue but she like wants to know pretty quick and doesn't want to take time off work so that plumbers can go and have a look.
I have done a quick search but haven't come up with much.
Any help much appreciated.