Range from the cheapest Fix a leak £240 (Tripleds Plumbing and Heating based in SE5) to the dearest Fix a leak £360 (LTT plumbing based in E1).
Comparing plumbers estimates for Fix a leak gives you an idea of who will be better value but the best way to compare costs is to get actual quotes.
What to do - Get rates and quotes for fixing a leak in your home by posting your job to plumbers in Se1p.

"Fix a leak, stiff stop-off valve"
E1
" Hi, i have a job that i need a quote for pls. -Toilet flush - once the flush re-fills it occasionally leaks water - it needs to be looked at. Maybe cistern overflowing. -The shower head holder is corroded and it's now broken - it needs to be replaced. Please can you provide a fixed price quote..."
SE14