I haven't the space to set up anything with lamps etc indoors for seeds at the moment but I found one of those mini-greenhouses in the shed, with a plastic cover. I'm not sure where to put it, I have a spot that gets full morning sun and then filtered in the afternoon, which is usually warm. I popped some on the hot water unit the other day and the soil dried right out so I am not sure full sun in a hot spot is ideal...

Olga
Everybody uses differnt method for cactus seed germination and get reasonably good result.
I use a mini-greenhouse and a heating pad with natural light.
When temperature of soil surfce exceed 40 'C, many cactus seeds stop germination.
Direct sunlight can easlily exceed 40 'C on soil surface in a mini-greenhouse.
No light is necessary for seeds germination but it is necessary for following roots development.
I keep the mini-greenhouse next to a window in my shed.
I use a heating pad and control the temperature of soil surface around 30 'C.
You should measure soil surface temperature setting the mini-greenhouse on verious locations.
If a location can keep the temperature between 20 to 35 'C, you can set the mini-greehouse on there.
I wap pots in the mini-greenhouse by a plastic sheet to minimize dried out.
Hanazono

Thanks for the advice, I'll check the soil temperature today I've got it on the pergola in a warm spot at the moment.