Sorry, need more info. First, which plants and are they in the ground or in pots, second, are the ants on the plants or just in the ground?

sorry! plants are all in pots on flat roof, so ants and slugs are on the flat roof tiles ,plants are passion flowers eucalyptus, an orange tree, which they love, various lillies,a rhodadendron and basically anything i try to grow! i use plant food, water regularly but not overwater and even sprayed diluted washing up liquid as told ants hate this, bug clear.flowers don't stand a chance, the buds are eaten before they open and black flies etc on underside of leaves,only the bamboo and a cactus seem to survive all other leaves shrivelled and brown on the edges

I wonder if it is Vine Weevil and not slugs? Are the leaves nibbled on at the edges?

Vine weevil infestation is a possibility, but I'd check the plants thoroughly for signs of aphid infestation - these look like either black or green tiny flies, or small black clusters of bugs, usually on unopened flowers and newer leaves or shoot tips. If you find an infestation, spray all plants thoroughly with a systemic insecticide, making sure you spray all parts apart from open flowers.

Second, the ants and slugs - slug pellets do work, so a sprinkle of these regularly should really take care of the problem. If the ants are ever on your plants, that'll back up the possibility of aphid infestation - ants love the honeydew they produce. Ants will also invade pots from beneath if there's nothing between the bottom of the pot and the surface they're sitting on, so raising the pots up on something is a good idea. Use something like pot feet or bits of broken roof slate, anything like that which gives clearance beneath, and dust beneath with ant powder. If you have ant infestation in the compost/roots, you'll need to turn the plants out, let the ants clear, soak the rootballs and then repot.

As for the shrivelled and browning leaves, that's most likely lack of water. With the heat we've had recently, keeping up with mature plants needing water in pots isn't easy - soaking morning and evening is essential. Water with a can with the rose off, or insert the end of the hose directly into the pot, not running too fast. However, some plants prefer a bit of protection from very hot sun in the middle of the day - this isn't usually a problem in the UK, but obviously, we've been hotter than the Caribbean recently, so some plants may frazzle because of the heat.

thank you so much for all the advice think you're right about the aphids will try out all your suggestions xxx

black peppermint is good for warding off ants. Put some in a bucket (a few stems) and add hot water, it will make a sort of 'tea'. (if easier use cold water, but leave for 3-4 days) After a few hours, use the water to sprinkle around anywhere with ants, they will pack up and move! I use this in my fruit cage when they make nests, or in the raised beds - they always move! I think they must hate the smell!