Jennifer Moore wrote:
hi people
1. Kitchen worktop of the kind made of thick chipboard with melamine
(or something resembling melamine) covering/edging.

Paint the exposed chipboard with PVA or varnish - most important, seal it
with silicone so the water can't get to it in the first place.

I have some matching edging, but what I don't know is what kind of
glue is best for sticking it on. Advice?

Evo Stick.

2. Little ceramic tiles with house numbers on. What would be the
best substance for attaching them to the house?

Gripfill or any construction adhesive, No More Nails etc.

3. Neglected external woodwork on a windowframe.

Any exterior wood filler.

Dave