By bedding I assume plants that you will discard in early summer for other plants. At this time of year you will be looking at pansies/violas, primula and bellis [double daisy] If you can still get them then annual wallflowers are a good bet. forget me nots may be for sale too.

If they are being grown outside then harden them off for a week or so, that means putting them outside during the day and inside frost free/cool shed/garage at night. If they are already outside then they can go straight in the ground unless it is frozen.

you can get small pots of bulbs that could be used as bedding. if you don't want to keep them for next year then just chuck them or you can plant them and have them year on year.

avoid anything that you would recognise from the summer as they will not survive any of the frosts. unless you have anywhere to keep them frost free then don't waste your money.

And if you mean summer bedding, things like geraniums, petunias and so on, none at all, its too early. They can't be planted out till mid/ end of May, depending on whether there's still frost about.