Limewash fills all sorts of Mister Meaners...........erhm, anyway.
It will fill hairline cracks, like the chap said. The reason your getting them is because the lime putty ( the white stuff in the bucket, remember, from your online crash course in building with lime) is full of water when its mixed and when it dries it loses volume and the render shrinks a bit.
The lime render won't have dried fully yet, but it'll be well on its way after a couple of weeks and will start to carbonate, go hard and become durable. It should have done most of its shrinking by now as it's been on porous brickwork in the sun and wind. All bricks except engineering bricks are porous, especially London Stocks which is what your house is probably built from, so don't worry about "Oooh, my bricks are all porous
". If you want to check that out, put a dry brick in a bucket of water and it'll bubble away nicely.
To make sure the cracks aren't getting worse, take a photo of them now and another on Monday and compare them.
Lime is a marvellous thing and by lime washing the wall you'll be filling the cracks with binder ( lime, think glue for sticking particles of sand together for making mortar products) and creating a multi layer, moisture permeable, weatherproof coating on the render. It'll last for about 4 years or so and need re-doing to keep it looking lovely and white. It's easy peasy to do and cheap as chips. You can get all sorts of colours to put in it as well, our lime wash on the internal kitchen wall has cobalt in it and is a fetching shade of blue and our external brick panels are yellow ochre.
A bucket of lime 20-25kg costs about £8 and to make lime wash mix 50/50 with clean water with a whisk ( one of those things that you put in the chuck of a drill for mixing plaster with ). Two buckets of lime make 100 litres or so of good lime wash and should be enough to re-do a semi with two coats. You can get all sorts of other stuff like casein or raw milk to put in lime wash to make it stick to timber and modern gypsum plaster, but it's not necessary for washing lime render.
Compare that to the cost of a fancy pants modern exterior paint. To make it dazzle white
mix Dolly Blue in with it, if you can find some in grandma's under sink cupboard.