You will have to split the bead from the rim and check the bead was not damaged on fitting.
Make sure there is no corrosion on rim inside and that it is smooth and clean, it should then seal.
Last resort use that tyreweld stuff
Not unusual. Could be a bit of kerbing damage or might just be some corrosion on the wheel. Tyre off, clean the wheel and a wipe round with the magic gunk stuff that the tyre fitters use with a paint brush and re-fit the tyre. If there's no obvious damage on wheel or tyre then it's sorted. Very rarely you could have a porous spot in an alloy wheel but, as I say, that's rare.
Thanks chaps phoned a tyre fella and he has come back to me gonna pop out take a look he also said prob needs a good clean bit of tyre sealant and refit etc. So I'm happier now as thought was going to be costly. Thanks chaps