If they are to go outside, then they don't need to be in the greenhouse. I have a bench agaist the wall and tuck them under there until there is something to look at You may need to protect them with fine wire mesh, especially crocuses and tulips, as mice and pheasants love them and if you have either you will be left with empty pots!Any of the small bulbs - crocuses, Iris reticulata, Scillas and Chionodoxa, outdoor hyacinths, loads of things. Snowdrops and aconites though can be difficult from dried bulbs and are best planted 'in the green', i.e. when they have leaves. If you don't already have some in the garden to lift, you can have a go, but get them from a good supplier to have the best chance of success.With daffodils and narcissi the smaller ones generally look better in pots, unless they are fairly large, or they look out of proportion. Grape hyacinths look good too, but the commonest one, Muscari armeniacum, has rather long, floppy and untidy foliage, so again choose some of the smaller varieties. Tulips are the stars of my pots, but it is usually recommended to wait until November to plant them to avoid the risk of a disease called tulip fire.Bulbs for the greenhouse are prepared hyacinths and narcissi, amaryllis and things that are not reliably frost hardy, such as ranunculus, or things you just fancy to bring on early, to enjoy indoors, like anemones.
What about some little alpines in pots that can be outside in the summer but that need protection from the combination of cold and wet that our winters provide?
https://www.gardenersworld.com/plants/10-alpines-to-7grow/Or why not visit somewhere that has an alpine house/garden Not sure where you're based, but I like going to the one at Cambridge University Botanic Gardens http://www.botanic.cam.ac.uk/Botanic/Place.aspx?p=27&ix=16&pid=2803&prcid=4&ppid=2803but there are plant of others https://www.telegraph.co.uk/gardening/3347043/Alpine-gardens-The-top-ten-to-visit.htmlWatch out ... they can become an obsession
Is a day out to Cambridge a possiblility ... the gardens and glass houses are only 10 minutes gentle stroll from the railway station ... you'd love it http://www.botanic.cam.ac.uk/Botanic/Home.aspxA good café too
You could plant some hardy annual seeds for early flowers next yearAny ideas which are good to last