I think you're unlikely to have very visible frogs all over the lawn, and the ones that do survive will get culled by the neighbourhood cats or the same heron perhaps. Frogs do a great job of keeping slug numbers down, so I'd say keep them and do not worry.

Yeah, only a few will reach froghood - wild creatures are good at keeping numbers within the bounds of available space.

Many of the tadpoles will not survive to develop into frogs. I always have thousands of tadpoles in the fish-free pond but don't have huge numbers of frogs. The frogs do not just stay in my garden but tend to disperse over quite a wide area, coming back in Spring to spawn.

Frogs are fantastic for eating slugs/other bugs.

When a pond has too many tadpoles many will die because there's not enough food.

I want as many to survive as possible so I add one crab stick each day to the pond. The tadpoles love it. They swarm over it in their hundreds and grow very quickly.

When they exit your pond you may see a few froglets on the lawn for a day or two as they make their escape but after that they'll find pastures new and you'll rarely see them again

Gosh I wish we had your 'problem' our frogs don't spawn in the pond. But we do get lots of newts:-)

Many thanks for all your help.
The reason I asked the question was that several years
ago we viewed a new-build house which we considered buying, until we saw the back garden. The large lawn was a seething mass of little froglets. All we could think of was a lawn mower ploughing into them! Ugh !
Thanks again.x

Even if you do get liottle froglets on the l;awn it is only a short lived problem. Soe jump away and some are taken by birds - you just have to be careful mowing for a week of two! I wish we had some frogs - we have one huge toad but he can't eat all the slugs himself!