simple plug hole question

I have to replce the plug mechanism for my bath. it is one that you turn a handle on the outflow and the plug pops up. The instructions to do this seem fairly straight forward so my question is what do I use to seal around the edges to prevent leaks? Is the compression from the screwed plug hole enough or do I run a bead of normal silicone around it or is there something else like a mastic that I should use?? and also can I get it from somewhere like B&Q or Homebase or do I need to go to a proper plumbing trade shop?

Thanks
Andrew

Depoends what they've given you but you usually don't actually need anything if everything fits.
In the real world it often doesn't quite sit where you would like. QUite often the chrome waste wants to tilt in its depression. If that's the case I prefer sanitary silicone (allow it to set) but the traditional material is plumbers mait.
Washers they give you should seal onto the outside of the bath.

If it is a plastic bath with glass fibre reinforcement, then use a sealing compound as well as the washers to make up the roughness of the underside. In fact, it doesnt hurt to use a sealing compound at all in all areas - it only takes an extra few minutes, but it gives you more peace of mind. Avoid plumbers mate too. It contains linseed oil and plastic baths dont like it. Silicone sealant is fine but LSX and Plumba are better. Wipe any residu silicone off with tissue paper as soon as possible, its murder to shift when it starts going off.

Plumbers mait?, not boss white then

Thanks for the advice as it is a plastic bath I will use sanitary sealent - I already have somem anyway so it will save a few pennies.

Andrew