The only way I know of getting rid of clover is to dig it out, making sure to remove all the rhizomes, not an easy task! You can remove the visible part of the fungi but it will continue to grow from the mycelium, a lot of thread like roots underground. Is this just in one particular spot in your garden or spread about? If just the one spot could there be rotting wood under the soil? Slugs are a bane for most gardeners you can go out at night a pick them off and dispose of or you can use slug pellets but only sprinkle a few of these around.

I agree with MG about the clover. Make a feature of it if you can't get rid of it, the bees love it! The fungi I think will grow regardless and is only there for a short while.
Slugs - well that's another matter. Slug pellets can be picked up by the birds and hedgehogs get them either by eating the pellets or eating slugs that have! A bucket of salted water, a disposable glove and a lot of satisfaction by picking them off by torchlight and dropping them in the bucket!

Thank you both for your comments. the clover has spread to a large area of the garden now so digging it all up would mean I would need to returf the area. Is there no weed killer that targets clover I can purchase? I like the idea with the slugs and will certainly try this. Thank you

Okay you didn't say the clover was in your grass. There are chemical weed killers, copy and paste the link to the RHS site
https://www.rhs.org.uk/advice/profile?PID=357

However it is getting a bit late in the day to use chemicals if you live in the north of the country.

Rampant clover in a lawn is also a sign of lack of nitrogen in the soil, since clover makes its own fertilizer.

we have used the typical feed and weed lawn treatment and that did get rid of the clover. hubby put an autumn treatment down and then a late spring one.

as for the mushrooms/toadstools they shouldn't pose a problem and the underground structures actually help in keeping the soil healthy.

slugs could be trapped in beer traps or hollow orange/grapefruit skins or pellets though pellets can cause concerns if you are bothered by the wildlife. certainly going out with a torch and picking them up and disposing off is possible too.

welcome to GoY too :o)