There's a lot of value in her playing without your guidance/entertainment....
Getting outside is so good for all kinds of learning/development. Can you walk to a playground or park? It's a bit chilly still, but in a month's time that would fill a whole afternoon. You also often meet other mums there, which is nice. On the walk there you can do sospicy - stop to pick up sticks, point out birds/squirrel etc. Kick leaves, stomp in mid or puddles... bring a ball to roll down the slide/under the swings/roll it round the roundabout (only if there aren't lots of other children!). Take a snack so you aren't under time pressure. With my eldest, I used to take a book and was stop and rest on a bench in the way back for snack/story so she wouldn't be totally exhausted when we got back.
Mark making is good at this age. What is your floor? Get a massive roll of cheap paper (you can buy these online). Masking tape it into the floor. Draw a box in it and give your child paint/crayons whatever and try to get the to make marks inside the box. We have laminate floors now, so don't bother with the box and my younger ones just scribble anywhere! For little ones, crayons can be hard and traditional paint messy. Chubb paint pens are great for toddlers and it washes out of clothes/off walls etc... Isometimes draw something in pen for them to colour in with the paint.
Playdough is great if you don't have carpet or if your child is very well behaved. Get some small knives and forks and roll it into sausages for them to cut up. Hide toys in it for them to "find" - my boys loved it when I made a swamp with Tony plastic dinosaurs hidden in it.
Do you have a bath? If they don't mouth too much,you can get jelly bath/slime bath kits. Might be better for when your child is 2, but it's a favourite of ours for really cold days. Again we make a theme - green jelly for a swamp, or orange slime for a dinosaur volcano. Youcan do it outside in a tray as well.
18 months is a good age for messing around with food. My eldest used to love mashing bananas. I'd measure the flour etc and we'd make muffins. Making picture with cut fruit is fun too (of course, they eat it. That was sort of the point with my eldest.)
One advantage of dark evenings - you can have a disco! We've got a disco light ball thing. My toddlers all love to dance to it with some music. Get out some unbreakable mirrors for extra fun. Light up bouncy balls also good.
Crafting things more generally I reckon will bw better in about a year. Stickers and magic painting will be real winners at that age, but at 18 months you'd have to be doing most of the work peeling offetc, which robs her if the pride of doing it herself.