Wildlife Gardener 123.. i am the same i have changed my garden round to suit bees and butterflies birds and all..
so for pots.. dwarf buddleha , dwarf cosmos, veberna rigida is ok in pots but is low growing so ok in beds also at front, nepeta.. dwarf lavender.. sedum to a degree and that is later flowering.. or if you have a wall/fence try some ivy growing up that provides late nectar and nesting and hiding places also..
or u can go for standard buddleha and plants also. they are good in pots..
but tbh not many are good in pots bar the summer bedding plants.. as they get dried out soo much. and if u want perennials to come each year they need to go in the ground.. really..
as steve309 said do bug houses.. and bee homes. for the last 3 years we have had bumble bee colony living under our shallet. its wonderful to watch them come nad go