I successfully replaced the syphon of my toilet, but on reattaching the cistern to the base, the cistern inlet pipe started leaking where it connects to the main water source. It looks like the rubber washer inside the valve is worn away to shreds. It may be quite difficult to tell from this photo, but the red bits inside the valve are just ripped to bits:

I'd like to know how best to fix this. Of the solutions I can think of, I have questions about it:
- get a new washer. In this case, I'm worried that a fixed 'lip' on the pipe would make it difficult to fit a washer. Also, how would I describe the kind of washer I'm looking for?
- replace the valve with a a service valve like this. In which case, will that be compatible with the existing pipe which looks to be fixed in place?
- replace the fixed pipe with something else entirely. In which case, might be time to call in a real plumber :)
Additional info: this is a UK house, these fittings are probably around 20 years old.
How do I fix a leak in this inlet pipe?
