16 month gap here, youngest now just over 6 month's. Its really hard work and there is nothing you can do to make it easy, but you can make things a bit easier for yourself. accepting that it just is hard was the best thing for me. Sleep deprivation is awful. But it's totally worth it! things that help me...
Let toddler help with nappy changing - passing wipes, sticking down tabs etc.
Lots of praise for being kind to baby (even if you're cringing inside....unless baby cries in pain, they're being gentle enough! )
Telling off baby sometimes so toddler doesn't feel they are the only one being told off
3 or 4 nappy changing stations around the house
A bag packed ready to go so if it all gets too much you can just leave the house
Meet other people when going out if possible. Not essential but can be helpful and also stop you.going out of your mind!
Cheap playgroups as you said.
Don't feel.guilty for keeping dd in nursery...do it as much as you can afford!
Accept help and ask for help if you need it.
Breastfeed if you want to and are able to...much easier than having o think about formula.
Go to bed as soon as you can and if your dh can sleep in a spare room and deal with dd1 in the morning it will really help.
Can't think of any more tips but although it's tricky, you'll get through the days somehow! And if you get a decent sleeper I'm pretty sure it will be amazing. The nights I've had 3 hours sleep in a row I've felt much more able to deal with things.