Advice please i have not long aqiured a garden before that it was all flats so?

never had a garden.so this suits my 16 year old persian cat , who gets out a lot in it in summer but only with me of-course , never by himself.he loves to lounge on the ground basking in the sun, trouble is when he comes in all those garden ants are all over his fur.and worse still i live in a studio flat so angus has Acces to my bed as it is just one big room , and therefore all those ants get in my bed from him.it is just something he has always done come in to my bed in the morning and goes under the sheets for a cuddle., and i wont stop him as id miss him. is there a spray i can put on him so when any ants went on him they would fall and die , a spray that would not harm angus, i know about the drontal for fleas but that takes time to work i think and he does not have fleas