My dog has never been a strong swimmer & I would like to teach her how to be a stronger fitter swimmer as she enjoys it but just struggles a bit.

What tips can you give me so I can go about improving this?

You should introduce her to swimming gradually. Some dogs can actually develop a fear of the water if they are rushed into it. (Not that I'm accusing you of rushing your dog ). Does she look more like she is exerting herself? Is she strong and get enough exercise?

A good suggestion would be to use any toys that she might have. You can play catch by throwing the toy and having her swim and retrieve it and bring it back.

Does it look like she can't support herself too well? Sometimes dogs have problems keeping their hindend afloat. If this is a problem, you can place your hand on her belly near her back for support until she gets accustomed to keeping herself afloat.

Shes quite storng & gets plenty of exercise, but she's heavey from all her muscle and has only got short legs bless her.

How can I introduce her to water gradually, I dont fancy getting in our local river lol as its filthy, should I try introducing her to it via a pool?
And she tends to sink at her hind end lol so I'll try what you suggested trying to keep her afloat with my hand. Thanks.

My dogs love swimming. I take them to the beach with me once a week so they can run and swim. They have been swimming since they were pups and have always loved it. I bought a baby pool and when were at home they jump and play in that. It keeps them cool in the summer.