Ideas for container plants.

I have several pots large and small and all I can buy at the moment are pansies. What other plants would be suitable and be flowering before June?

I'm not familiar with your climate or if the containers are able to be relocated if the weather turns a little to chilly, so forgive me for misinformation for your area.
I have grown marigolds from seed to flower in less than 2 months in containers.
Will other flowers be available in the next month? There are a wide variety of annuals that flower quickly when purchased as plants.
Our favorites for our window boxes and containers are geraniums, alyssum and sprays of babys breath.

I don't know about the UK, but over here nurseries tend to focus on selling things that are blooming because that's what catches people's eyes and makes them want to buy them, so they sell those rather than things that will bloom in a month or two. Since we're getting into spring, I bet if you keep going back to the nursery every few weeks you will find more and more plants besides pansies.

Our weather is changing from unusually warm for March to cold and chilly which is more normal for this time of year. Although I know that it's early for bedding plants I was just hoping that there might be other plants that flower earlier suitable for pots. I can put the pots indoors if the weather gets too cold or wet.

Not sure IF you have done container gardening before but here in UK we are kind of between seasons, I've got pots of Daffodils tulips act, but these were planted Autumn last year to flower from Feb to end March. but there are other winter / spring bulbs to try for next year.
As for this year there are things like Primroses, / and other look-a-likes that are in the garden centers right now but, to be honest, mine are about finished flowering now and I am ready to plant them outside to grow again for next spring along with Cyclamen etc.

Right now March/ April, I am tending my next lot of bedding plants for my tubs, baskets and pots and these are Fuchsias both upright and trailing, Geraniums upright /trailing, Tagetes (Marigolds all colours /sizes) Scaevola, Verbena's, just to name a few, but I wont be planting those outside till end of May as we get snow sometimes before then (I am up in Scotland) as you know we have had a really hot sunny spell last week and now forecast snow for Easter Sunday, ha, ha, ha, fore seasons in the one day.
Anyway what I do is start to plant up my tubs / pots etc and keep those in my greenhouse or undercover till they are hardy enough to plant out, they don't need a heated area just bright and frost free.

If you really want to do pots outside right now you would really need to buy some evergreens ready to size like Yucca, Pieris, Pinus but then you wont be able to use these pots again as these plants are year round,
Unless you have to have pots in flower for the next few weeks then if I were you I would be testing my patience and looking in the garden centers as to what is already there, the cheapest way now at this time of year is to buy what we call plug plants, these are small plants that you need to pot up into larger pots and care for them till they are large enough to go our side end May, but if you have room at home you can buy trays of plants much larger and still care for them but they are not so tender, they have already been potted up and this dictate the extra cost of this size of plants. My only tip would be when you do fill your pots, don't be too sparse with the plants, I try to squeeze as many plants as I can into the pot so when the grow, they are overspilling the pots with their blooms.
Hope this has helped you out and for next year you can prepare way ahead of each season with regards to pots. good luck. WeeNel.