As for the plastering,
The trick is to lay it on, let it dry a little and then smooth it out. The more you play with it (the plaster) the wetter it get. It needs to left alone to dry a little before you make it nice and smooth.
DIY, this is what I did too. Invest in some good tools. You really do get what you pay for...and this:
www.amazon.co.uk/Collins-Complete-Manual-Albert-Jackson/dp/0007425953/ref=sr_1_1?ie=UTF8&qid=1399899878&sr=8-1&keywords=diy+book
Known as The Bible in this house and it's saved me a fucking fortune.
The first year of this crap is the hardest, as it's all the milestones that you have to do on your own BUT..it's a lot, lot easier after that first year. I promise you, it's not as bad you think it is and look what you have done so far. Look what you have acheived so far and look at what you are planning to do...3 months on and you are making plans! It took me twice as long to get to the stage you are at now.
I don't want to sound patronising, but think PRACTICAL. It makes life a whole lot easier, especially when you are ill. ALWAYS overstock on loo roll, bread, milk, calpol and nurofen. It's the little things that can tip you over the edge, like having to drag them both out to go to the shop for milk because one of them has drunk or spilt the last of it..which you forgot to get on the way home from work. Again.
Online banking, online shopping, online food shopping are god sent. Use them and take advantage of them. Do everything it takes to make life that little bit easier...even a steam mop has helped me as it's quicker and easier to use than the whole mop and bucket farce.
Use the calendar, makes notes and keep looking at it. Deal with paperwork straight away (this one is easier said than done), mark it on calendar, or put money in envenlopes for trips or bills and then file them away.
Take up as many offers of going out as you can. Build up a new social life for yourself.
Everything will get easier and easier as each month passes. That I can promise you, as can others.