What is the best way to seal the junction between a bath and tiles?

Buy a set of bath trim tiles ,the design is about 80 years old but fill a gap neatly, they come in a set enough to do around a bath ,they are ceramic and glazed and come with fixative

first you need to set the midpoint as a bath moves/flexes as it is filled so fill the bath 1/2 full leave for five minutes then use a good silicone one with anti mould properties,run a bead around the bath then take a spray bottle with water and washing up liquid and spray over the silicone you have just applied make sure it goes o the tiles and bath. then using a silicone smoother or a lollipop stick to smooth down the silicone the excess will collect on the smoother/stick dispose onto a piece of towel this is the best way to get a pro joint.dont bother with the masking tape wayas it leaves a a lip that water gets under and ruins all your hard work :)

Plastic quadrant beading

Bath edging strip will work you will need two lengths. I would try to fill the gap with silicone as well just in case water finds its way passed the edging strip as water only needs a pin hole to get through. Hope this helps.

if the gap can,t be filled with silicon sealer ,,try an aftermarket flexible cover..from B&Q etc ..they come in different colours and sizes..

make sure bath is fixed securely pump mastic down sides of bath that touch walls level with top of bath when set tile down to bath leaving a 5mm gap between tile and bath when tiles are set seal 5mm gap with coloured waterproof mastic of your choice

Why is there a gap in the first place?!

hi you can use a plastic tile bath trim which is self adhesive ,l shaped with a rubber edge. this sits on top of your tiles and overlaps your gap.

Use some Plastic beading (or another) to reduce the gap.