Had problems with these recently - suggest you check fittings which attach to pottery base are metal with washers and not plastic-type, and check that diagrams/instructions are actually useful - ordinary, not-soft-close-type from B&Q (own-brand?Lewis&Cooke-or-similar-name) was not impressive.
The lacquered MDF ones never seem to last, and eventually water (and other fluids...) get under the lacquer, and it has to go.
I bought a nice one recently from B&Q that was designed to be easy to clean - no bumps and crevices on the underside of the seat, made of quite a heavy-weight plastic and neat stainless steel hinges. Soft close too.
I like the Ikea ones which are less than £10! They are heavyish duty. the nuts/wingnuts for attaching are plastic but last & the seat easily adjusts to the perfect alignment before you tighten said wingnuts.